Yes, it is normal to put on weight after surgery. Remember, you had UC which was robbing you of nutrient absorption not to mention playing havoc with your GI tract. Now that you are "healthy" your body is absorbing calories normally. I found that 5 years post j-pouch surgery I had gained 34lbs! I have since shed 24lbs of it.
I don't quite understand your stomach bulge but can tell you from my experience it took about a year for my abdomen to look normal again. There was lots of distortion due to the incisions but it eventually went away.
dx proctitis in 1987
dx UC in 1991, was stable until 1998
1998 started prednisone, asacol, pentasa, nortriptylene, ativan, 6MP, rowasa enemas and suppositories, hydrocortisone enemas, tried the SCD diet, being a vegetarian, omega 3s, flax, pranic healing, yoga, acupuncture, probiotics
2000 lost all my B-12 stores and became anemic
2001 opted for j-pouch surgery- now living life med-free