Boyfriend doesn't believe that I never had sex before him

I am 17 years old and last tuesday i have sex with my boyfriend and my vaginal was to large and i never had sex before.because my vaginal was to large he stop having sex with me that night because told him i was a virgin but i know i was virgin cause i never had sex.but now i still can't believe if am a virgin or not cause his penis didn't go that far on my vaginal.i didn't feel anythig while we were having sex even after but i don't know what could cause that ,cause i never had sex before.please help me!!!!!!!!!!