Couple of questions I need answers?

Hi, my name is Tara and I'm 20 yrs old. I am american. I am currently working in the nursing field. I read that there is a very limited chance of a foreigner actually getting into the nursing field. (Registered Nurse to be exact.) I also read that the JET Programme is also available for Teaching English in Japan. So basically my job listings are very limited if I plan to go there in the next couple of years (about 5 years after I finish college). I am also teaching myself Japanese since the beginning of this year. Will this help me in the future??? Are there any jobs besides teaching english??? Will I be too old by then???
As far as size goes, I am a Size 18-20 in U.S. sizes (yes I am plus size) but I'm trying to lose weight by then, if I drop down to a size 9-10 in U.S. sizes, would this be a good size in Japan??? I'm also the hour glass shape tooo....
Please someone help me out, and thank you very much for reading!!! (plz no rude comments)

You're never "too old" to do anything, but since you are a student, have you considered coming to Japan as an exchange student? With your student visa, you can wash dishes part time, and if you're lucky you can also teach English while doing some job scouting for your future. And teaching yourself Japanese will indeed help you in the future, the skillful the better.

I'm not familiar with American clothes size. You'll have to write down your measurements. But I wonder what you mean by "good size." Any size is good as long as you are healthy and proud of yourself at the same time!

As Uco says, as long as you are healthy, a "good size" is whatever you are. Clothing in Japanese chains other than Uniqlo tends not to go much past about a US size 6 I am afraid, and the range of sizes is very small. I take a US 6 in pants and skirts, and I am an L in Japan! There is also Zara, Gap and H&M for a somewhat larger range of sizes. To be honest, beyond a US size 10 you would be mostly restricted to plus size clothing stores and sections.

Don't do anything extreme though, your health is the most important thing!

I am 5'9", so a lot of clothes here are not long enough for me anyway- I just buy from Zara, or when I go overseas. The lack of choice I have here in clothing has probably saved me a lot of money!

Thank you sooo much and I'm not in school yet... I start in January..... but I will definately ask my college about it if they offer foreign exchange.... now would I be living with someone or my own apartment. (sorry never really been explained about the foreign exchange before???)....