how to finish!!

First of all im on antidepressants which might be a cause. ive only seriously masturbated like three times. i got a bullet vibrator and i really like it. sometimes i find spots on my clit that really make me tense up and feel good. buti think i am too worried about finishing to actually finish. i havent tried with vibe while sexting my bf cause he is unpredictable. maybe that would help?! im kind of scared cause i know a lot of women dont orgasm and i want to.