Healthy Weight Gain?

I am currently 16.5 weeks pregnant. I have gained about 5-7lbs so far. However, I got pregnant just 6 weeks after having my daughter. So I never had the chance to lose any of my weight from my first pregnancy. I gained about 40lbs with my first pregnancy and to be honest I did not eat as well as I should have. I was 205lbs when I delivered my daughter. I was then 188 when I got pregnant again. I did manage to lose a few pounds and I remained around 183 until recently and I am now 192. I am so fearful of gaining too much weight with this pregnancy. I am trying to eat healthy and exercise but I am not sure what I should be gaining? My doctor is not concerned with my weight.