eh, this is tough donjuanit0. you can only postpone the eventual conversation, if you're actually gonna take the relationship seriously. i started out telling my girlfriend "well.. i was gonna get a t-shirt for number 500, but i guess 497 is worth a tshirt too..." lol but she kept pushing. she'd try, wait a week, try, wait 10 days, try, etc. finally, i said "listen, i don't want to know about all your sexual escapades dammit!" she was practically in tears, and said "you're number 2." so at that point i thought... alright, i actually see some potential in this girl, so i'll let her know, so i did.
anyway, to answer the op's question, 10 is a lot for a 19 year old. lets just LIBERALLY estimate she started having sex at 16. 3/year, 1 every 4 months.
enjoy getting her pvssy for 4 months. dont catch feelings. girls like this dont do it for me. you have an evolved desire to not want girls that have had a lot of d1cks inside em because that raises the chances that you're gonna be raising the PRODUCT of one of those encounters.
it comes down to what YOURE comfortable with. some guys on here are totally okay with it and can put it out of their minds. I know i cant. if i knew something like that about any girl that i was trying to game, i would immediately stop any attempts on her. if you dont like it, then you dont like it. not the end of the world, plenty of girls out there.