PLEASE HELP

I have been desperately trying to lose the last 15 lbs. I have been going to the gym for awhile now. I have done classes with weightlifting primarily and cardio, with some recovery days with yoga. I have also started the keto diet somewhat recently. I feel like I am trying my absolute best but my body is fighting me. I am still currently breastfeeding my 1 year old. Could this be the problem? It seems like I'm holding on to the weight mainly in my belly. Up for any suggestions. Y'all are the best!