This story makes absolutely no sense. You state that he was moaning about how big you are and that HE might have put his penis in? Sorry, but the story is incoherent.
Everything else you mention is NO RISK, not "low risk" as you stated. If you think you were penetrated, or you penetrated him, get tested. You've been around long enough to know when to test and what test to take.
No comment on the needless hand-wringing over the extraordinarily unlikely chance that you'll be positive. "Feelings" have nothing to do with whether you do or do not have a disease.
A knowing feeling * sorry I posted it too soon on accident. But yeah I’m pretty calm about it right now but if the test comes back positive who knows how I’ll react tbh.