Postpartum weightloss, upset :(

So I only gained 19lbs total in my pregnancy but I was already chubby before getting pregnant, so I was greatful I didn't become huge.

I went from 169lbs to 188lbs... 2 weeks after delivery I weighed and was down to 172lb, I am exclusively breastfeeding, so when I saw that, I was excited.

Clearly I will need to work out after my 6 week postpartum check up but I thought that maybe if the weight keeps falling off so easily I might end up better post pregnancy, well I haven't been doing much but staying home full time with the baby and trying to balance that and sleep is enough work for me.

Currently 3 weeks postpartum and weighed myself and I'm up to 178lbs, I'm not eating excessively, I don't know why I'm gaining weight.

Help advice? Anyone else go through this? Postpartum meal plan advice? breastfeeding meal plan advice?