Firstly, WELCOME!! BellyBelly is a great resource & lots of knowledgable people (I do not claim to be one of them!)

Second, have you considered natural therapy assistance? Using accupuncture, naturopathy, and other streams of NT can have a huge impact on both of you. Vitamins are one thing, but I doubt they'll have a huge impact on conception.

I think that you both need to have your fertility assessed by your doctor, or have a referral to a fertility specialist. You don't necessarily need to have any physical uterus/ovary issues to there still be a hormonal issue.

This is a page that contains tests you may be likely to encounter:
Fertility Specialists of Western Australia ? Infertility Investigations

Some one else is bound to post something infinitely more profound than I have.

ETA: there you go - Lulu said charting your cycle! VERY VERY clever suggestion! It's all about mucus.

But I wish you all the luck.