You can definitely max out all your skills without losing any of your virginities. For example, you can always rub your vulva against another woman's for perfectly safe vaginal skilling, or you can work at the brothel's gloryholes for guaranteed control of sexual encounters (though you don't get paid very well for it...). When you're engaged in consensual sex, you can also ask your partner(s) to not penetrate you (and they'll give you either a yes/no which the game is kind enough to not lie about), so you can have guys rub/tease you without penetrating, which also works for skilling. And if you want, you can also get a chastity belt to reliably protect both your vagina/anus until you're ready as well. As I said, there are definitely options if you want to play a specific way - I know, because I do as well!