Weight gain

Early In my second trimester I gained my 1st lb. now I'm 28 weeks (3rd trimester) and have been gaining like 3 lbs every week . I'm up 7 lbs total Is this normal ? I still have 12 weeks left , so I don't want to gain 36 lbs if I'm gaining 3 lbs a week , because I was already overweight to begin with . I know people will say "don't worry about the number on the scale..as long as you're eating healthy, etc etc." I just want to know if the weight gain that fast or normal or not . My appetite is always weird so I don't eat the best anyway and I'm so exhausted every day that I can barely function so I don't exercise .

FYI: I don't have preeclampsia , Gestational diabetes or anything like that . My pregnancy has been great .