Completely Different Pregnancy

Pregnancy + 3 year old + 32 hours/week (on average) working as a nurse sure takes it out of you. I am exhausted again. At this point in my first pregnancy, I was commuting to San Francisco and working 24 hours a week, taking 3 nursing prerequisite courses, including 2 of them with labs, walking 5 miles a day 6-7 days a week, my house was spanking clean and I was positively g-l-o-w-i-n-g. This time around, I'm lucky if I walk twice a month and housecleaning? Forget it. What started to appear as that infamous second trimester glow 4 weeks ago has disappeared again and I'm just tired, tired, tired. And massive. And already waddling. And my skin is crazy broken out. And my back pain sucks. And the round ligament pain can be brutal. And I get these killer headaches sometimes. And I crave salt AND sugar all the time. And before anyone asks, I am technically fine and my MD is not concerned at all...there are no real health issues or danger signs...it's just that this pregnancy is soooooooooo different. Girl? Or am I just old?