Whats wrong with my dating sense?

why do i date people that i know i dont really like, for example, im 18/f and i was dating this 24 y/o. it was cool at first. we didnt go on a date. he took me to coney island, drove mes to his and was telling me he liked me a lot and he wanted to preform oral sex on me, i didnt know what to say, he asked for a kiss so i gave him one, and then when he was driving me home, he told me he wanted to have sex.......in the car..so he was goin to park it somewhere so we could do that.. im telling you, these are the type of things that make me cringe at boys, why could you not wait until it was the right time and place, you wanna bone me in the car...ugh, sometimes i think this happens to me because i have low self esteem and i look like a pushover, then he gets mad cause i dont want to do it, and everytime we are together he wants to do it with me, i dont understand, maybe im not worth to get to know, ....i dont know, someone help me out!