I always direct people who are starting out to this site:
http://www.choosemyplate.gov/myplate/index.aspx
It's a great tool to see how many calories YOU should be eating a day based on your age, height, weight, gender and the amount of exercise you do. Also, the food plan is all about healthy eating - feeding your body the good stuff 3 times a day! I think 2 meals a day isn't good for you, because your body might be storing things away to compensate that you aren't feeding it regularly. Obviously, not everyone can just hop on the healthy eating bandwagon, it took me a few months to realise that I actually wanted to, but nevertheless it's a great guide to start you off on educating yourself on healthy eating.
I've read in multiple sources that if you're excising consistently then you should eat 5 meals a day but divide the calories up to suit your style. Personally I don't have time to do this because of my job, so I stick to 3 and try on a day off to snack on fruit to fill me up.
Water should be worshipped. It's just a fact. It hydrates you and it helps with your weight loss like you wouldn't believe. So replace that diet soda (gradually if you're used to it and can't go cold turkey) with water.
I agree with kaplods in that time based goals are stressful. If you don't meet your "quota" then you might get upset and then lose faith in yourself. You just cannot afford to doubt yourself during a weight loss journey, you have to be strong willed to get through. So if I were you, I would think about your goal in a different way, think more like "I will lose as much weight as I can before my birthday."
I wanted to be 150 lbs by February 11th a few months ago. If I lost my usual 1 lb a week I would have achieved it. Well it's January 1st and I'm 162 lbs - life happens and you just have to deal with it and not let it get to you. Am I upset I won't reach it? No, because I've still come so far and I'll reach it in my own time!
I think you should most definitely start using your treadmill. Get on it for 20 minutes a day 3 times a week at least and break up a sweat. Even if you sweat by walking fast, that's fine. In time you'll get stronger and you'll be able to go faster. Exercise is so important to weight loss.
So is your goal achievable? Maybe, it's definitely not unreasonable. But if you have faith in yourself, if you can stay dedicated for all that time then you can do it. I believe anyone can lose weight if they really want to, but they have to really want to change. Because that's what it's all about really, changing your lifestyle to become a healthier person.
I wish you all the best, this site is an amazing source of support and inspiration. I don't think I would have had quite the same success as I've had so far if it weren't for this message board!