Wanting to get fixed but don't know what side effects there are?

Briana • Married to my wonderful Husband Brandon Hayes ♡ we are pregnant with our 2nd child and we are happy to announce it's another sweet boy ♡ can't wait to welcome Braxton Layne Hayes ♡
I'm fixing to turn 22 and this is my second child I'm about to have. I have always wanted 2 kids an no more. Two boys are enough for me, would love to have a girl but how my husband's side goes that won't happen and I'm okay with it. I don't want anymore kids and my husband definitely doesn't want anymore. He wants to get fixed also but I don't know if it would just be easier for me to do it after I have my son. I know I'm still young but my sons are so close together and even if I did want more it would be for a long time so they would end up being to far apart. Anyways, my doctor keeps trying to talk me out of it but the thing is I'm allergic to birth control and break out in hives so I can't have it. I just want to know what the side effects are after you get fixed as in do you gain a lot of weight? Bleed alot? Or is it normal like you never even got it done but just won't get pregnant????? Help!