First, congrads on working towards your RN -- it's a highly rewarding job. I work with many RN's and admire their dedication.
Also, mother nature changes your body after delivery. The body tends to retain fat more stubbornly. Because in the olden, caveman days, if food ran out, the mother can still survive for her children because of the retained fat. Unfortunately, it's no longer the case in this day and age, but our bodies still have that 'programmed' in there to do that after delivery.
I also gained after I had my little girl. I found it impossible to go to the health club, being that I work full time and sooo tired when I get home. And, with the weather being so dreary 9 months out of the year, it's hard to get outside and take a walk, or hop in a car and drive to the health club.
So, we changed our basement den to a work-out room. We got a used elliptical, some dumbbells for weight training, and a bench to do the weight training on. And a TV to keep us entertained as we sweated it out. Now, I can go downstairs and excercise after she goes to bed.
If you are limited for space, then u can get Tae-Bo videos. They are fun and really tone u fast, esp your butt and thighs. I had used them when we were in an apartment, and saw results in 2 weeks already. Their "boot camp" version is really good. If you use excercise bands along with it, it even makes it tougher.
So basically, like the others said, you need to burn, burn burn. U can eat salad all day, but if you are not burning the calories, you won't lose anything. And, if you eat very little, your body will go in 'starvation mode' where it will retain ALL the calories you eat, and u'll gain weight. Eat sensibly, like with Weight Watchers. So start doing any cardio exercise, at leat 30 minutes 3-5 days a week. Eventually, try to do cardio up to 45 minutes. U need to rev up your metabolism. Good luck.