OHSS is one of those things that's not really worth worrying about. If it happens, it happens. On the first cycle they threatened to abandon it because I had prefaced a silly number of large follicles, but when they tested my eastadiol levels (E2s) they were 2000 which is well within normal range. So they went ahead with egg collection, though I had a reduced trigger shot, and harvested 12 eggs.
With the second fresh cycle I proceeded more large follicles, I can't remember how many, it was in the mid thirties with a lot that were over 20mm. My chart was a picture to be honest. I didn't feel bloated or dizzy at all, in fact I felt better than I had with the first cycle. However my eastradiol levels were 14000 and although they coasted me for three days, they kept rising. The cycle was abandoned as my clinic decided that I was too much of a risk for OHSS if they did egg collection. OHSS occurs after egg collection.
With the third fresh cycle, I was on a very low dose of the stimming drugs (half the dose of the first cycle) and egg collection was after 9 days of stimming. A lot fewer eggs (only 6 mature enough for ICSI) but no overstimming drama.
I don't have PCOS, we have male factor issues, I'm young ish (28) and my body just loooves those stimming drugs! Really though, don't worry about it. Having a cycle abandoned is tough, but your clinic will do everything to make sure that you stay well and don't have OHSS issues.
Good luck xxx