Long read plz help

Sooo here’s the whole thing; My last period was 1/30-2/4 so by default I was supposed to ovulate 2/18 and start my period 3/4. But my period never came and at first I thought it was just late or being weird but I had a lot of EWCM 3/4-3/6 so looking back I think I ovulated then instead. Either way I had a dr appointment on 3/13 and got a transvaginal ultrasound finding two cysts and was prescribed exactly three months of birth control and to start taking them that day. But if I didn’t ovulate until the 4th and it takes 18-21 dpo to even see in an ultrasound let alone get a BFP. If I did ovulate on the fourth I would not get my period until some time around 3/18. I’m very worried about what to do. If by some flying chance I got pregnant on the 4th and I started taking Sprintec Birth control on 3/13 could it harm the pregnancy? I’ve heard women getting pregnant on the pill and it not harming it but I’m worried. I don’t want to stop taking it cause I’ve already started and it’s only for a 3 month time span so I’m trying to finish ASAP... Im taking another pregnancy test on 3/20 if I don’t get my period still but I’m just not sure what to do at this point. I told my nurse I thought I ovulated late and all she said was maybe or you might have had an anovulatory cycle so I think they’re just assuming I didn’t ovulate at all 😒😒😒