When I was trying to up my milk supply and lessen the bottle feeds with my DD, I would put her to the breast before a bottle and aim for at least 10 mins, give her a bit of the bottle and then put her to the breast for as long as she would take it. I would also try to offer her booby in between feeds. And we coslept. It felt like she was on the boob all day. But by the time she weaned when I got pg with DS when she was 7mths old, she was down to having 2 fairly small bottles a day.
I was on motilium too, taking the most I was allowed to, I think it was 90mg a day if I remember correctly (it was over 3 yrs ago!) I tried the fenugreek, but it made DD really windy and gave her belly pains, so I stopped. I would try to make sure she had a big feed in the mornings when my boobs were particularly full. This was the only feed for a long time that she would happily take and not have a bottle after, I loved this feed!! Another thing is to try not to stress about it. I know ti can be hard when all you wan tis the best for bubby, but the best is for baby and mummy to be happy and relaxed because it will affect both of you if you're getting stressed out.
There are other natural things you can try, milk thistle is supposed to help with milk supply. Drinking planty of water and eating a healthy diet will helo too. You can try aktivite (an additive you put in milk, a bit like milo, I was drinking tonnes of this each day, luckily I thought it was delish!! If you really want to do it, you could try a supply line, it's a little tube which goes onto your breast and leads to a supply of formula in a pouch, so baby can suckle at your breast and stimulate your milk supply, but still get more formula at the same time (does that make sense??). There are teas which are supposed to help also (though I can't think of the name of them.)
I see that you have other kidlets too, so it may be hard for you to be giving baby so much of your time. When I was trying to up my supply, DD was an only child so I could do it, and dedicate lots of time to it all.
Good luck.