First I need to address your eating habits. I dont know why your not eating meat but I assume its a personal choice that your not willing to change so all I can say is make sure your getting all the vitamines you need that you would normally get from meat. Also, eating so much sweets and so much soday is very unhealthy, and I'm sure that overload of processed sugars is what's making it difficult for you to fall asleep.

The good thing is I wouldn't really consider this "insomnia" quite yet. I suffered from insomnia for a long time, and I reached the point where i would stay awake for 3 or 4 days at a time, that can lead to severe stress and even hallucinations. I started to diet and drastically changed my eating habits and I developed a routine where I spend a few minutes meditating every morning just after I wake up and every evening before I go to sleep. Now I have a normal sleep pattern and my dreams are as vivid as can be, and I am improving my lucidity every day. I was able to change and my case was VERY severe so dont lose hope. Since your still a minor case you have a great chance at improving your sleep with sime work

Good luck