Follicle and Canceled Cycles question.

So I start Letrozole/Femara tomorrow and then start Gonal F on Saturday. My ultrasound is the 9th of February. My nurse said they will check to see if I have enough or to many follicles on that day. She said if I have to many or don't have any at all, we will readjust and try next month. What is to many? If I have what would be considered "to many" can they make me not try or can I go ahead and trigger anyways. I see people saying they canceled that cycle. Do they actually cancel it or just advise you not to do it and let you choose? My husband and I desperately want a baby and after two years of trying and $600 a month on shots, we both want to go ahead and try no matter the number of follicles. I've read a ton of articles and talked to people who had "to many" and a majority only ended up with 1 baby or no baby at all.