I hate my body but I cant work out ):

I was 104 pounds before i got pregnant and then after my c section I was 125 pounds. I got Nexplanon birth control and now I weigh 165 pounds ): I want to work it off but I have awful knees and i have short tendons in my legs and feet. I was born with my legs and feet turned inward. I had to wear casts up my legs from my feet to my hips for a year and then shoes with metal soles for years after that. When my neice was born she had the same issues and i learned that they now have a surgery that they perform in addition to the casts and shoes that corrects the issue. I never had surgery, just the casts and shoes. I started cross country training in high school and ended up having severe problems with my legs and feet. I saw a podiatrist and they told me I had to stop running because I was risking tearing my tendons since they are short. I cant touch my toes or lift my legs without bending them at least 90 degrees. With all the issues i was born with it gave me very bad knees as well. My knees are in constant pain and only got worse after having a baby. I'm 25 and i feel like a knee replacement is going to be necessary within the next 5 years. I just feel so fat and ugly now. I wish i could do cardio and squats without injuring myself and I wish I never got this birth control. Before pregnancy and now pictures included.