I haven't seen any Nepali females but there are plenty of Indian females in US army.I am not sure about the age bar but i think if you are in your 20s or 30s you should be alright.And if you have bachelor's degree you will get enlisted as E-4 (SPC), and if you have few college you will be enlisted as E-3(PFC) and you are just out high school make sure to tell your recruiter that you can bring some more people in the army and give some names he has power to enlist as E-3 , if not you will be enlisted as E-1.So, better try your best to come as E-3.Here is the link which will tell you how much push ups , sits ups and run time you need to pass your physical test.Make sure you are able to get 60% in each event before you go to see recruiter, that's all you need.It will make your life lost easier.
http://usmilitary.about.com/od/army/a/afpt.htm
And get some job in financial department or computers you know something like paper pusher or if there is nothing available get something related to aircraft mechanic.These jobs are easy, risk free and will give you lots of experience for yr civilian career.
If you wanna know anything else just let me know here, i will be glad to reply you.