I don't really know what a normal weight gain is, but if your MW is worried I'm sure they'll say something & advise you about diet & exercise. The weather is brightening up, so maybe start going for walks the fresh air will do you good. I always find it easy to have light salads & fruit when Sun is shining But in the beginning I just wanted crap! Cheese, crisps, mcds! A wise mumsnetter said you want salt in the beginning cos your body knows you can't get food posing from crisps & junk.
I'm 16 weeks and have put on 10lbs, so similar to you OP. I feel big because I was at the max weight I am comfortable with when I got my BFP, but I am not stressing. It can come off once the baby's out.
There is no 'should have'. Just try and eat as healthily as you are able and be as active as you can manage. That might be brilliantly healthy and still running at the gym at 17 weeks. Or it might be only able to stomach a small and horrifically unhealthy list of foods and barely able to lift yourself from the sofa.
FWIW, I have (in three pregnancies) gained a lot in the first trimester, very little in the second and then a moderate amount in the third. I also, sadly, seem to be genetically programmed to get a pregnant arse. Every time no matter what I do!
I'm 34+4 and I've put on 33lbs! I blame the staffroom cake and biscuits for most of it. Now I'm on maternity leave and the sun is out I've been enjoying long walks and salads rather than quick grab food during my lunch break. There's no "should" weight gain, we are all individual.