This is a question from a young person, so here's an answer for a young person:
Ask not what the girl has done before and what she can provide for you now, but instead, ask what you can provide for her and whether being a virgin will affect your feelings for her.
Wake up! There's no point guessing about her virginity. If she is willing to tell you the truth, she would have already. Since she hasn't, your relationship with her is not at a trust level she's comfortable to discuss this yet. You have 2 roads ahead of you now, a) be patient and continue developing this relationship, or b) continue being obsessive over her virginity and eventually drive you and her nuts.
To answer your question, NO YOU CANNOT GUESS because it will never be the fact.