how much weight are you supposed to gain?

Hi mummies! I've entered 2nd trimester and now gaining alot of weight. I used to weigh 58kg before pregnancy, 50kg in my 1st trimester (the nausea and vomiting was really bad, and I had no appetite), and now I weigh 55kg in my 2nd trimester because I'm eating more frequently. Is such weight fluctuations bad? And how much weight do u gain throughout pregnancy?