How much should a 16 year old female weigh if she is 59"(4feet 11inches)?

i am this 16 year old that is being spoke of in the question and right now i bounce between the weight of 96.6 lbs and 101.2 lbs and this is within days time. i have a feeling that i may be underweight so i started eating more and having big dishes of brown rice that was cooked with maybe a cup of shredded cheddar cheese and a cup and a half of cubed beef and a tablespoon and a half of jalapenos that was minced. is this enough, am i unhealthy, should i be worried? oh and sense i go to college i take spinning and i don't want to drop the cl sense i need the grade to help bump up my average score. help me! what should i do to stay at a healthy fit weight?!