Virginity is kind of a cultural thing, rather than a medical thing. It just means you've started having sex (typically referring to penetrative sex)
Your partner might be particularly large (especially if their penis is thick, as that actually has more to do with sensations during sex than length).
The bleeding could have been from your hymen tearing, and then the second time tearing more (most likely if the second time was more rough or if it was in quick succession).
The best solution is to make sure that YOU are aroused before having sex. If your vagina isn't properly lubricated, it can be uncomfortable or painful, even if it's your 100th time having sex. Bleeding can definitely happen if you're too dry. Make your partner engage in foreplay, or just do it yourself!