the pill and bleeding

So my baby is now 2 months old and being the cutest little potato. I went to my 6 week check up everything was great. I'm exclusively pumping just because of some issues we had in the beginning needing to know exact amount of food she was getting and now it just kinda stuck and it works for us, anyways. I started the pill and ever since I've had a period. Cramps and all. it started with spotting from the 3rd day I started and now it's a full on period since the 5 day. Has anyone else experienced this? Will it go away? I had never taken birth control of any form and this is really nerveracking. It's been 2 weeks now.