I don’t know what to do tbh

I was dating this girl from about a month, but every time id say i wasn’t ready to have sex because

1. im hella self conscious

2. im 14( a baby ik)

she would get upset and cancel plans on me??? it was really upsetting, and thats not even all of it. she would also talk to her exes and about how hot other girls were, saying how much she missed someone she hooked up with of “how nice the girl in front of her’s tits were.” im a very jealous person by nature and normally it doesn’t get to me but ive had feeling for her for almost a year now and it was tough for me to watch. after she dumped me she reached out saying we should reconnect this summer and was implying getting back together. I said no, but i like her a lot and i kinda wish i’d said yes. what do i do?