Amy, I was on Antagonist protocal both times and now going into 3rd one same way. I believe you mentioned you are dealing with MFI only, so are we. It is fairly common to have a short cycle when BCP is not used. I have never used it in any of my cycles either.The reason that most clinics use BCP, is a couple of reasons from my understanding. One certain bigger clinics typically like to have cycle only certain times of the month, anotherwords they will have everyone of their patients on same schedule so BCP keeps it to that schedule. Other most common reason is to help surpress system especially on Lupron protocals. It is also used when cycles are very irregular helps keep her on track. I did not use it because my cycles were regular, so RE felt no need. Plus she has her own practice so she does not do certain cycles.
So the answer to your question is YES, it is very normal to stim and do er. I will actually start on monday and ER abt on 1/23 and transfer 5days later. Best of luck to you!!! <3