Pregnancy weight gain!

I'm about to lose my mind!
I'm 22 weeks and have gained nearly 20lbs! 
I started at 128lbs and am now 145lbs,
My thighs and ass are huge and covered in cellulite!
What is making me lose my mind though is that the first 3-4 months I was severely sick, I couldn't hold anything down! 
I've always eaten healthy, only drink water, the only thing that changed drastically was my exercise level, I was so sick i was bed ridden most of the time. How did I gain so much weight?!
I'm so depressed and have never felt so disgusting and embarrassed about my body in my life.