Gonal f vs follistim and ganirelix vs cetrotide

Hey everyone, I just got my period and they started me on BC but I recently got my calendar and they have me on follistim and ganirelx. I had a canceled retrieval a few months ago and have already ordered gonal f and cetrotide for that cycle. I asked what the difference was between the two medications and they said there were interchangeable so I asked if it was ok to take the gonal and cetrotide since they weren't used for the previous cycle. They said it was fine. Now I'm having second thoughts because Im wondering why they switched meds? My first retrieval we used gonal and cetrotide and got 5 blasts with 3 pgs normal embryo but none stuck. Maybe im over thinking it. I just want the best possible outcome. What do yall think? Have you used both and what was the outcome? Thank you, sorry for the long post.