Can you please clarify what " slept with him unprotected since march 9th 2021 i got negative pregnancy test march 2, 3, 4 i got all negative pregnancy tests, then march 9, 10, 11 i got all positive tests" means? If you got back together with your boyfriend February 11, does this mean you began to sleep with your boyfriend again since February 11? What does "since March 9" refer to?
("me and my boyfriend broke up january 29th 2021, i dated my ex was with him for only like 3 days maybe a week, we slept together only like 3 times unprotected, he never came inside of me, i got my period heavy feb 6th 2021 to feb 10th, i then got back with my bf feb 11th") It looks like you're saying you and the boyfriend were only broken up about 12 days and then back together, and nothing happened with the ex on March 9 or any later time than maybe February 6. Just please clarify when you slept with your ex.
If you only slept with your ex at the end of January/first of February, then your boyfriend, not your ex, would be the dad.
Please read the notes at the top of this community, it gives you a list of what to do and when (especially early in the pregnancy) to get an answer about when you got pregnant.
I suggest strongly you go see your doctor and get an ultrasound as soon as you can, meaning, pretty much right now. If your ob/gyn won't give one this early, find one who will. Explain that your cycles are irregular and you don't feel you can rely on the date your last period came, to give you a conception date or a due date.
The due date they give you from an ultrasound should clarify when you conceived. If your period came when you were all done having sex with the ex, that is also a clarification that the ex is not the dad. having had your period after the time with him. Your negative pregnancy test as late as a month later (if it was a month later) than the sex with the ex, is another indicator.
To get a more specific due date, you need an ultrasound, and the sooner the better for this, since they aren't as accurate for this purpose as time goes on.