Need to stay focused!

Hi, I've been on MFP for a few weeks now figured it's time to introduce myself. I'm 28 female, 5'5" weight fluctuating 140~143lbs (cheap scale so I don't trust it's accuracy). I'm looking to lose another 15-20lbs or go down from a size 8/10 to a size 3/5. I used to be a size 0/1 and then had to leave my job and couldn't find another so my life wen't from very active to sedentary. I also gave up smoking almost 3yrs (would be 3 in November) and I compensated all my cravings/habit of putting a cigarette to my mouth with food. I had a wake-up call when I went on a mini-vacation with a couple friends and realized how great they look in bikini's and for the first time in my life.. I had to wear a skirt with mine because of how embarrassed I was with the weight I gained. Since then I put myself on a diet. No more dinners of fritos + chili, no more soda (was really hard to give up), no more candy, and got myself to get up every day and exercise. Started off with this thing called "the wave". I never used it as intended except the step exercises. Either way I was 163lbs... I dropped about 20lbs since November last year. It's not as fast as I had hoped but weight loss is a life-style change. Took a while to realize that but I'm happy to be on the right track. I still have lots to learn which is why I'm glad my friend told me of MFP. I can track what I eat and how much exercise I get as well as the vast amounts of posts of information on fitness and nutrition. Glad to be here and hopefully I can reach my intended weight goal by the new year.