What the ladies above says has merit, but I have a different take based on my own experience. I got pregnant with our first child at 32, at that time I weighed 225 and I'm 5'-2", so near the same level of obesity that you are at 5'-4". Anyway, I was completely shocked that my file was in a pink folder, which at my doctor's office means "high risk". Okay, yes I'm an asthmatic, over 30 and obese, but high risk?
Well to make a long story short I was the picture of health, gained only 30 pounds and had an easy natural delivery (if such a thing can be called "easy"). Which I followed up with 10 months of breastfeeding, which was difficult at first but totally worth it. By the time she was weaned I was down to 210. We've since had 2 more children, with basically the same story, high risk folder, picture of health, natural delivery and months and months of breastfeeding.
I found great maternity clothing at JC Penny's, ordered everything on-line and had it delivered to the local catalog drop for free.
One thing I might add is that you have to remember that being pregnant is one thing, being a mom is a completely separate issue and a full time job for years on end. Truthfully it might be easier to be pregnant and go to school than to be a new mom and start back up. Seriously. So if you take a year off to concentrate on being pregnant, how are you going to face dropping off your brand new baby for 12 hours of daycare? Just a question. My doctor actually told me that her average OB patient is 36 years old, and her average first pregnancy OB patient is 32. You didn't really say how old you are, but maybe there isn't a big need to rush this?