I put on 15 kgs with bub 1. I lost 8 of those kgs. My bub is now 2 and I'm 20 weeks with bub 2 and so far I have gained 4kgs. I hope this means I might only gain 8-10 total but I'm unsure if that's possible.
OP we all gain and lose at different rates, but there are healthy guidelines based on your BMI prior to getting pregnant. Do a google search and it will tell you. If you are outside of that range and you are concerned, talk to your midwife or GP or obgyn about it.