120 lbs and the size 3...

So I go to the doc for a physical, which of course means you get weighed. I expected to be 116 lbs, as I was ALL summer...she puts the thing on 100 then moves the little things to 20...BOOM!!! WTF??? OMG??? Seriously??? Ok now about  a year or two  I wanted 120, but that's because I was at 89lbs...(yeah thats a long story that DOESN'T involve anorexia or Bulimia). Don't get me wrong 120lbs is ok. Its heathly...sorta, I am 120lbs, and its all because I eat cakes....these to be exact:






and I drink this  everyday (without ice). I don't exercise although I have a gym membership. I feel awkward at the gym. I have gotten quite lazy walking the dog and he has gotten lazy too. So my point is that 120lbs is not healthy if you are eating crap. But I have no initiative to change and I really need to because I have a beer belly and no beer. I am 28 and don't want to grow any further, one my height, two health.
A size 3...in juniors for the most part, every now and then I have to either go up or down in sizes, which really pisses me off and sometimes its my body and sometimes its the company's idea of a size three, like skinny i was doing a size 3 until I bought my levi's skinnies...I had to go up because i need my knees to bend. Cheap brands im a 3 usually, when price goes up the size does too at times...and dress pants...the worst...I tried a 3 its too big, I try the 1 its too tight.... What I am is a solid size 2 (ok maybe not solid once again depending on the brand) but this takes me from juniors to misses, but in the average department store size 2 is like looking for a needle a haystack not to be cliche, but I work in a clothing store albeit juniors but I see that the smaller the size the less they have. On the racks they have like two size 2's. By the time I get to it or its on sale (I love a good clearance rack) there are no pants for me. (shirts are getting bad too because my arms are turning fat as is my stomach) I gotta dress like this by March or next August 2013: 
LOL...(but seriously there will be pics if I make it March or August happen)