Should I worry??

So I just had a baby he is 3months now. At my 6 week check up I got my birth control pills and took them for a month. After that month I stopped them because they made my breast so achy and very uncomfortable. I then got back on the pill 3 weeks later and for the past 5 days on and off I’ve been getting kinda like menstrual cramps but no period. I am fully breastfeeding my baby no formula at all. I pump a little when I go to work. Also I didn’t get my period after birth until I took the pills that one month I got some bleeding when I stopped the pills I had no period again. I took a pregnancy test Tuesday and it was negative it’s now Friday and I’m still freaking out because of the cramps and no period. I know periods tend to be all over the place after birth and also breastfeeding slows down the period. Should I still be worried even after my negative results?