Any time you have sex, you are at risk of becoming pregnant. Cum or no cum, there is always precum. Did you use a condom? Birth Control? If not, the risk is higher. You need to take a pregnancy test as no one on here can tell you whether or not you ARE indeed pregnant. As for the other question, "how i'll understand that i've loose my virginity", I cannot answer that as the question itself confuses me.

You lost your virginity.

definately lost your virginity. thats the definition, having sex is lost virginity. and to see if your pregnant take a hpt.