As a 21 YO virgin I'd recommend Australia's ACON 1st. http://knowtherisk.org.au/risk-calculator/
There's some very good and up to date info there. Condoms, PrEP, an Undetectable partner or Negative partner IF and only IF you can be sure they ARE. Talk about it and ask questions. Don't assume anything, If you don't know or can't be certain use a condom or get PrEP.
Just because you are a Gay virgin doesn't mean you don't have an STI from a hetero encounter. Get tested and treated if necessary.
I like A4A, you can filter for many things, like "no drugs" or build type and age. SCRUFF and apps like that don't say enough. Make sure your first time is a good one, you will remember it for the rest of your life! We all remember it, good or bad!
(Sorry about the links, my tablet or RJ isn't compatible!)