Gaining weight !

So pre pregnancy I was at 120lb and now I’m around 126lb at 13 and a half weeks. I have a big appetite throughout the day and mostly want junk or sweets! I work out just about the same as I did before(running hiking etc) but I have a problem with constipation which is super annoying. Any tips? Trying not to gain so much weight so rapidly so soon! Or maybe this is normal ? Idk I’m a newbie to all of this.