38 weeks pregnant, weight gain

At first I was joking about it all the time, but now it's really starting to bother me. I've been gaining about 5 pounds a week, pre pregnancy I was about 145. I now weigh about 220 pounds. Can someone relate? Please give me some kind of guidance because I'm really starting to feel bad and a little insecure about it. I'm starting to get stretch marks all over my body because of the weight gain