more comfortable

i’ve been talking to this guy for a year and some months now and he was my first and after my first time we did it like may 2-3 time but it wasn’t long either times and it wasn’t because of him it was because i was too in my head... idk why but i’ve only seen my body so it’s just new. i want to know how i can get more confidence and be more comfortable with sex and different positions... some positions all i can think about is how i look and then i start thinking and get in my head. help please.