Acacia, there is some good information around on breastfeeding and fertility treatment. There was a good thread here recently which I can't find right now, but I've flagged this for one of the other mods who was posting in the thread. You might also find this podcast interesting, it is by an ABA counsellor who has gone through fertility treatment while breastfeeding and who has done loads of research about it all - MumsRight Podcast (scroll down to talk number 22 in the grey box on the right).

All the best hun.