I am a NASM certified personal trainer and although (right now!) I haven't exactly been practicing what I preach, I will provide some advice. I don't think your goal is unreasonable but you need to have an "I would be happy with ____ lbs lost, but I'm shooting for 30".
You need to buckle down and not just diet- work out as well. I have an extremely high powered job so trust me, I'm trying to figure out the balance here myself, but just dieting isn't going to cut it if you want that much weight lost. Cardio 3-4 x a week, 5 if you can swing it. And STRETCH your muscles AFTER you work out!!! SO important!
Also, be realistic. If you go out with your friends and one of them has the chcoclate volcano brownie ice cream thing, take a bite, enjoy it. Just don't eat the whole thing. Dieting is about changing your everyday habits, not about depriving yourself.
Also, DO NOT get discouraged if the scale stays the same one week in the middle of dieting. This happens, it is perfectly normal. I promise, if you keep at it, it WILL move the next week.
Vary your eating- do not make yourself the same things every single day. I have this problem when dieting because I am a vegetarian and I feel limited so I end up eating the same things and getting bored. Try new ideas, look up low fat recipes.
Seriously, we all know the struggle, I'm with you right now. Just don't get discouraged. There will be times you will be frustrated, don't let it ruin all the hard work you've done. You WILL see results, I promise.
PM me if you need ongoing support... I'm here for you!!!