Large follicle?

I had an U/S yesterday and the only follicle she found was 28.5 mm. I usually have 3-4 follicles 1 being the biggest and the biggest they've gotten was 18. I've read some women post about large follicles saying when they got a BFP it ended with a MC and one on here said hers was a cyst and not an egg. Anyone else have such a large follicle? What was your results? BFP with MC, a birth, BFN, cyst? Thanks.