Feeling confused!

Right so I came off birth control at the end of September as me and my partner are trying to conceive. AF has been pretty regular, maybe a day or two out and lasted around five days. This month, AF started last Thursday, very very light, continued like that for four/five days give or take so I took a pregnancy test in case it was implantation bleeding, it was negative (I wasn’t surprised, I just wanted to rule it out) So anyway I thought when Sunday night came/Monday morning I would be starting to come off however it went the other way, I got heavier and I’m still bleeding now, seven days later!? Anyone know why this could be?