Another weight gain topic!

I just wanted to see if anyone else had the kind of gain I have? 
Until 12 weeks only gained 2lbs, then from 12 weeks to 21 weeks I've gained an extra 19lbs!! 
So all in all, I'm 21lbs gain at 21 weeks... But I don't feel like I've gained anywhere majorly but my belly and boobs... 
I'm terrified I'm going to carry on at this rate. Be 40-50lbs up by birth?! 😕
Anyone else gaining mad amounts?!