It's time for a lifestyle change. I've read through the FAQ, but I'm still feeling overwhelmed and could use a little help getting started.

I've been through a lot lately, and having never been one to take an interest in fitness and eating well these events have not been kind to my body. I recently started college which didn't go so well due to my recurrent depression, but I've come to realization that I need to change things in my life and I'm working to do so. Now that the depression is more under control and I'm feeling better about myself and my life, fitness and eating well are the next steps for me and I'm hoping I can get some guidance. Here is my basic info, taken from the FAQ:

Weight: 132lbs (~60kg)

Height: 5'1" (~155cm)

Sex: Female

Age: 19

Goals (weight loss, muscle, etc): I have no current way of measuring my body fat so I've been looking at my BMI instead of weight alone. Though I'm considered to be at a healthy BMI, I'm only about seven pounds away from "overweight" and I don't want to get there. My primary goal is to lose weight and drop some of my body fat percentage, but I'm also looking to strengthen up the muscles in my body as I've never really exercised outside of high school PE. Overall, I just want to be healthy.

Any injuries or disorders that we should know about? No, though I'm a very picky eater and I'm concerned about how negatively that might affect my diet. I don't like red meat or fish and I don't care for most vegetables.

Do you smoke? I do not smoke or drink (never have).

History of diet or exercise (What have you tried? What worked? What didn't?): I tried dieting along with P90X for about a week, but due to the negative effects of my depression at the time I wasn't able to keep myself motivated enough to continue with it. Aside from that, I'm a complete beginner. My current diet consists of diet soda, water, chicken, fruit, and a lot of crap. It needs to change.

Do you have access to a gym? Yes, but I can't afford a gym membership at the moment. I would also prefer to exercise from home if I can make it work.

I did read the FAQ and feel as though I have a basic grasp on the fundamentals of fitness, but I don't know how to begin; I don't want a repeat of last time where I tried for a week and slipped back into old habits. Should I stick with P90X as far as exercising goes, start with something lighter, or try something completely different? Would it be better to jump right into a whole new diet, or "wean" myself off my current unhealthy habits so the cravings aren't as strong? Are there alternatives to red meat and fish that are just as good for me, or should I suck it up and learn to like them? Any help, advice, tips, comments, or anything of that nature is greatly appreciated. I did read the FAQ thoroughly, but if I mentioned something here that was already answered there then I apologize. I'm also more than willing to answer any other questions about myself if needed.

Edit: I'd just like to mention that I only drink diet soda, water, and the occasional glass of milk.