Help worried I’m pregnant!!

Hello ladies! I JUST had a baby 8 weeks 3days ago! I am on birth control now, have been for 2 weeks! I waited to have sex until after 8 or 9 days post birth control insertion (nextplanon) only had sex twice. I am breast feeding! I’m worried I might be pregnant again! With nextplanon I don’t have periods, I had it for 3 years before I took it out and got pregnant 8 months later. I have been having some symptoms recently, like the last couple days. Headaches, nausea, lower tummy pains (diarrhea was my sidekick in pregnancy, couldn’t escape it 😭) I also just had a little bit of bleeding for the first time on my toilet paper!! My son has CF so my husband and I decided we would never have kids again via naturally and would do ivf later in life. I’m so scared that I could be pregnant again! Will wait a couple more weeks before testing!