No period in almost 3 months plz read!

Jasmine
Hi ! A few months ago I went to see my doctor about me being on my period for almost 3 weeks and they prescribed me birth control . So 28 days later I still haven't had a period and still now a month and so later I still have no period..
I thought I was gonna have my period a few weeks ago cause I spotted a day or two and then nothing !!
I did take a pregnancy test a few weeks ago and it came out negative but I don't know about now and I'm just freaking out ..if anyone has any advice please please please . My ears are open !!!!