The one common thread I have picked up is to keep being open and talking....

I've booked in to see a counsellor to talk as I don't want to discuss things with friends or family - its too close.
You are fantastic! I think this is a really good way to go.

I am not quite in the same situation as you as we are not in the LTTTC boat, but there are similarities in our relationship struggles. Our sex life suffers due to the more mundane life stressors... too tired... schedule conflict... too stressed.... too stuck in our own worries and concerns....

I think he sees me as more mother than lover now.
I understand what you say about your DH seeing you more as a mother than a lover. I have had real issues with exactly that in the past, in fact I still do! For me however it often is more of an issue in my head rather than an issue for my DH. When I am tired and fragile I have the tendency to focus on the negatives, and listen to the statements which confirm my paranoia rather than be balanced and realise that I am in a way creating my own reality! Hence, open communication is really important. It may not be that way for you guys. You may not have quite the same 'negative' self talk I sometimes have, or maybe your DH is actually having trouble with the whole mother/lover thing. (I am not saying this is the case as I don't know all the details, just playing devils advocate to think things through!) I think the best solution to this is to keep the lines of communication open. Sexuality is so often about the way we present ourselves. By that I mean that if you only play the role of mother - it may be hard for your DH to see beyond that. Perhaps if you talk to him about your sexuality and being a lover, he will seeing you in that way and you remind him of that side of yourself.

Amidst a drama and tears he told me how our infertility affected him sexually -
It is fantastic that your DH is able to identify this as a concern for him and is able to communicate this to you. But I am confused, did the infertility affect him by making him question how he felt about you sexually or about how he performs as a sexual partner? If he has concerns about his fertility, it could challenge his perception of his role in your sexual relationship which is not really related to your role as a mother or a lover. This mother/lover issues will be more likely to come to the fore with pregnancy and motherhood but may not be so much of an issue with conception struggles...??? Not sure but just a thought.

Its come out that he's been looking at stuff on the internet, which has made me feel quite anxious.
Men and their sexuality are so different from ourselves in some ways. They are said to be really visual sexual beings. ie turned on and ready to go by seeing something 'sexy'. Its like their sexual neural wiring is between their eyes and penis! See something sexy and ready to go for sex. This is why Porn is such a strong magnet for men. For women however, we tend to really need to be turned on in a 'thoughtful way', our brains have to be involved! We need to feel it, to have a 'story', to feel loved, supported, appreciated both physically and emotionally and to be touched in a way that wakens us up! And this is why porn just doesn't make sense for us!!! As a matter of fact it is often just stupid for us as there is no story line (or some flimsy plot to get to the action) and this is just insulting to women!

My personal approach to this is that I actively encourage my DH to check out Porn! I understand this is definitely not for everyone, but the way I felt is that it is something that *most* men engage in and I would prefer to have an open honest relationship and have an open discourse about it than force him to lie and cover up his interest in porn. I think that because I have not made an issue about it it has taken away the 'naughty' aspect of it which takes off some of the excitement and desire to check it out. I have checked out some of the porn he has and I am rarely offended by it. (I think he is only really into the mild stuff by porn standards). I think it has actually helped our sex lives as we are able to be open about it and he can be quite turned on to see this overtly 'sexual' side of me. (a bit like what I was talking about before of presenting yourself as a lover not a mother. Mind you, this approach is not the only way!)

I can't help worrying that it could get even worse after the baby arrives. Even now he's hesitant to have sex as he's worried he'll hurt the baby or something will happen. I'm not at all used to him not wanting me as he had a very big drive when we were first together, and I'm worried that if he doesn't desire me anymore he'll need to find it somewhere else.
It is great that you are able to air these concerns with your DH, as then he is aware of the situation and can understand where you are at. There is heaps of information on the net about why it is impossible to hurt a baby during sex. (as a matter of fact I have heard that the rhythmic movements involved in the actual act can send a baby in the womb to sleep! (Actually, prob not something he wants to think about!) Maybe if your DH is really uncomfortable you guys can find ways to be intimate without the 'actual' sex act while pregnant?

We are such good partners in so many ways and I thought everything was going great. He said he didn't want to hurt me by telling me how he was feeling, but it hurts me more that he didn't share with me so there was this sneaky element
.

This is huge, you guys have a good solid relationship, you should be fine if you keep working on this and don't let it undermine what you already have. You are so right, as are other posters here that the really big issue is the sneaky element. It hurts much more to have a partner do things behind your back which impact upon you.

Lastly (sorry this is soooo long), our sex life was pretty good during pregnancy, (I had a really hormonally increased libido!) and sex following the birth of our DD was also good (after recovery) as we felt really close and tender after sharing such a huge thing. More recently, life has just been so hectic for poor DH (2 jobs etc) and I am not coping with a badly settling baby so things are on a go-slow at the moment.... but hey, I reckon that is life! ups and downs!

Hang in there and put in the work to get over this. Its worth it! Remember, you are one sexy mumma!