Frequent intestinal discomfort

-I have been experiencing intestinal discomfort more frequently this year, and have become concerned because my symptoms are more frequent. I have been experiencing fatigue, constant nausea, loss of appetite, loss of interest, loss of concentration and focus, become full easily, light-headedness, and sadness. I also know that I cannot properly digest dairy products and certain starches such as wheat and oats. I have visited a gastroenterologist and have been informed about digestive diseases such as IBS, Crohns Disease, and Celiac Disease. I have had blood drawn and have given a stool sample in order to determine what may be my problem. But so far every test has come back negative, and I am becoming deeply confused. I am staying away from dairy, wheat, oat, and gluten products/foods to try to lighten my symptoms, but it seems no matter what I do I still experience all of the symptoms listed above everyday! I am beginning to lose hope in the medical care system, especially because I still don't have an answer. I just want to be able to enjoy my life again, and I can't remember the last time I actually felt normal. I really would appreciate some advice, information, or guidance. Thank you for your time and patience.

-KeeptheFaith94-