Hi sodium, you are not alone - many people suffer from this even from a young age like yourself.
A good site to get info. about IBS is www.helpforibs.com/
or just type in IBS and google for some info. there are many sites. A young relative of ours has the same problem and she has to keep away from coffee, alcohol, high fat foods etc. as these items trigger an attack. Things good to eat that shouldn't cause an attack are: bananas, mushrooms, potatoes, carrots, oatmeal (porridge) rice and pasta as these soothe and regulate the digestive tract.
Re: feeling panicky, that is understandable. When you feel that way just take long, slow, deep breaths inflating your lungs fully, and that is calming.
Also, (and I know you will probably pale in horror at the very thought) it is possible to wear a hygiene pad inside the pants as this would relieve any worry of 'having an accident'. ( I'm not being coarse, just trying to be helpful.)
Good luck.