I think it's good that you've started to make healthier choices, but don't start dieting! See your midwife before you make any decisions.
I've put on "too much" (nearly 3 stone, at 25 weeks, haven't weighed myself since... I'm now 33 weeks) but I have excess fluid, so that's the weight - not really the rest of me! Also, because I've become heavier on top (you know, growing a baby and all that) the muscles in my thighs and bum have strengthened and grown to support me! Yes, I've put on some fat round my bum and thighs as well (i think), but I will need that for breastfeeding afterwards! Everyone tells me that I'm "all baby" and this includes my very direct mum and sister!
So, please don't get carried away with trying to lose weight. It might just be how this pregnancy is going to be. Eat healthily and be active, but don't worry about weight!
For all those wondering, I had a normal, but low BMI of 19 when I was weighed at my booking appointment.
Please see your midwife if you're worried. Ask for an extra scan to measure the fluid - I had one at 28 weeks which showed that i have excess fluid. They sent me for the gd test, but it came back negative so it's just one of those things. I was really worried when I first weighed myself, but now I refuse to get concerned about something largely out of my control. I think you should adopt that attitude too!!!
Also, I know your dd is refusing to get in the buggy, so you're not walking as much, but could you go swimming (when your dp is home, perhaps?) It's good exercise and very supportive of your body during pregnancy. Just don't do breaststroke legs.