Other people have said it but here it is straightforward: keep your size to yourself. Seriously, nobody needs to know, and those that do will find out in due time.
You sound almost exactly like my husband in that he thought that women would be afraid of him. That's quite silly, actually. I mean some will if you scare them, but the ones that count will not.
I actually was not aware of my husband's size until later. I was going to say "until it was too late," but you know what I mean! LOL!
No, seriously, your size is that last thing that anybody needs to know. That's not the worm on the hook that women are looking for. Your personality, ease of conversation and just being a genuine person will attract the right one.
Nineteen is kind of a fragile age. You're thinking "Oh my, I'm going to be 20 and I've never been with a woman!" Sounds like a travesty in this day and age, but I find it quite endearing.
Just be yourself and keep being nice.