Feeling discouraged with postpartum fitness and weight...

So after giving birth my body obviously did it's thing with shrinking back and all that but at about 8 or 9 weeks pp I have started gaining weight back and quite fast and I'm not sure why... I was so happy with my body right after birth that now I'm feeling discouraged when I workout that I'm just putting on weight :/ I have never been able to breastfeed all that well (I'm insulin resistant and anemic so that makes breastfeeding a bit of a struggle) so i don't think that was ever a huge factor in my weight.... any other moms having a bit of an up and down battle with weight where it came on suddenly?