Frustrated

My daughter is two and my son is 5 weeks. My two year old starts mommy and me swim classes soon and I had to buy a swim suit for it. My body is just not me. Mentally I feel like I look like my pre-pregnancy self. Then I see a mirror, photo or size label in the new clothes I'm having to buy. I've never been this size. Even with my daughter I shrunk down pretty quick. We went to the children's museum today, I tried to go through a tunnel made of tape with my daughter and couldn't climb up it! It hurt and felt like my pelvis was falling off!! Like I have zero core muscles. I'm sore and sad now. Feel like something just isn't right with my recovery. But, the main mental block is my size. I just want to be fit and feel good! Sorry for ranting. But it's just so frustrating!! I'm dreading these swim classes and I honestly don't want to. I want to be excited to splash and swim with my daughter! I fear the swimsuit and the pain!