First period after birth or not?

Hi mummas!

Not sure if this is in the right thread or not but hopfully some of u can help me.

I've got 4 boys. New bubs is only 18 weeks old.

My after birth bleeding lasted for roughly 10 weeks possibly 11. I think i had a period straight after it in that but it sorta continued on. Im not sure if ive just had another or not. 

Heres abit of background: on microlut mini pill and have been for just over 3 months, breasfeeding and only just started some farax as per health nurse request. Some nights he sleeps through others he gets up and has breasmilk in bottle. So i dont always do nightly feeds on the breast. 3 days ago i woke up and thought i started my period, brown blood when i wiped, nothing progressed tho well not enough for the pad just a few times when i wiped. Then next day i had bright red blood, enough for me to think yep its here so wasnt streaks it was a decent amount (This is how it always starts for me) however after a few more wipes in the morning when going toilet it stopped and i have had nothing since. Ive had cramps still like its coming. Took pregnancy test night of red blood and next morning both Neg. Only had intercourse once at least 20+ days ago and used condom as well as being on pill so dont think there is a chance of pregnancy. Is this my period do u think? Breakthrough bleeding? U think i would know after 3 previous babies but i got it easily after them. 

Thanks for your help, please let me know if this happened to u xx