If a hymen is stretched or torn ,can it still cover your vaginal hole partially?

Yes

Am a virgin,started having sex with my boyfriend 3months ago,at first it hurts but I started getting wet and aroused,d pain reduced,he can easily go in ,he's small and sometimes he goes rough and sometimes normal,I know he's been stretching my hymen but and whenever I look at my vagina the hymen is still there but what worries me is that as he stretching the hymen it will still remain its normal size and it will still cover the hole partially,because my hymen is pretty very small and since we've been having sex,its been the same size.

Hymens vary a lot in size and thickness. Some are as thin as paper, and some are thick and tough. So there is no 'normal' and there is nothing to worry about. Why are you worried? (PS: You say you are a virgin, but you aren't anymore.)

If you are having sex you are not a virgin, if he is having sex, sometimes rough I doubt the hymen is in tact still