Hi there & Congrats on your pregnancy!
I was in the same exact boat: 1st pregnancy was perfect, even weight gain, for a total of 35lbs. But my 2nd pregnancy, I was so ill my first trimester that I lost weight, then really made up for it in my second. I ended up 10lbs over my previous pregnancy gain at the end of my 2nd trimester! I was able to taper it off a bit my the 3rd trimester, but was feeling very overweight. The bummer part of this is that I couldn't fit my old preggers clothes, so I had to buy pants to wear for the last 6 weeks! My blood pressure also rose significantly during that time (I normally have extremely low blood pressure, so it was alarming). I was really fatigued at the end of my pregnancy, too (due to the extra weight, due second time around?!?).
At 6 weeks after birth, I started a low-impact workout program at Lady Circuit (like Curves). So far, I have lost weight 1-2 lbs a week (while breastfeeding). I'm hoping to be back in my work clothes by Aug 2nd (when I return to work).
In retrospect, if I had a "do over", I gave myself the freedom to eat 2nd trimester b/c I hadn't gained at all 1st. I was feeling very low energy, so when I could eat again, I ate with a vengeance. I wish I would have been a little more restrained. But it's hard, as you have discovered, 2nd pregnancies have much stronger hormones.
I drank a lot of 2% milk to ease hunger btw meals, fresh fruit, FF yogurt. Trader Joes has these little packs of almonds that were really helpful to have stashed in my purse for "hunger emergencies".
Best to you!