Please Help me! What is wrong with me?

What is wrong with me? PLEASE HELP!?

Hello I am a 16yr old female

- During the beginning of summer (early June) I weighed 125-30 lbs ...I now weight 100-3 lbs

I didn't exercise ....in fact I ate a lot of desserts and junk food (like most people do when they're traveling and enjoying summer)

I've had significant weight loss and every morning I feel nauseous - I usually don't eat breakfast but I always eat a lunch, dinner, and snack. I take vitamins. Also, my eye sight has slowly deteriorated over time...I used to have 20/20 vision, but now I'm struggling to read things that are 7 feet away from me. I'm also having troubling remembering information....for example I'll walk into a room and forget why I went to that room or I'll ask a question like 3 times or I'll try to memorize a vocab word and completely forget it. What do you think is wrong with me?

My parents don't want to take me to the doctor, because they think I'm fine.

Overall my main symptoms are:

- Headaches

- Occasional Nauseousness/Dizziness

- Weight Loss

- Memory Problems

- Decrease in eyesight

I also have an irregular period (missed it for all of summer)...idk if that help