Weight gain...

I'm 14 weeks preg, and one of my pregnancy apps tells me I should have gained 3-4 lbs at this point lol. So I weigh myself. I've gained 15. That's over a lb a week. I used to be overweight and got down to a good size which I've maintained over the years. I had my son a little over a year ago, I had gained about 20 lbs total- and lost it all by 6 months post partem. I am getting concerned I'm gaining weight too fast this time, but not doing much different than I did last time. I know. I'm preg it's not a big deal. Husband tells me all the time.  I guess I just wanted to vent!