21 year old with normal blood sugar and some diabetes symptoms... help!

Is it possible to have diabetes or other blood sugar issues with normal blood sugar? When mine has been checked it's been about 103 an hour or so after eating a snack. But I have been having lots of strange symptoms for several months.
One symptom is frequent lightheadedness, usually about two afters I eat, or right after eating a large meal. Today, two hours after eating (three medium eggs, a slice of gluten-free bread and a slice of cheese) I started feeling really irritable and also lightheaded.
I also get frequent nausea, gas, and bloating. And I sleep for a really long time and wake up feeling exhausted.

I'm only 21 and these symptoms are really debilitating. I haven't been able to work or go to school and I am getting so frustrated with this. I feel absolutely terrible.

Thanks. I think I might be having reactive hypoglycemia. I'm planning on buying a blood sugar meter tonight. I'm not on any medications.

Lindsay, it could still be your blood sugar dropping or it could also be your blood pressure dropping.  Sometimes blood pressure drops after eating, but in any case, you really need to speak to your doctor and explain what's been going on.  Keep a log of when these feelings happen and for how long, what you were doing before then, when you had eaten, etc. to help the doctor understand if it's anything to do with the blood sugar or blood pressure.  Of course, if you could know what those two readings are when you're feeling light-headed, it would answer some questions and eliminate some possibilities.  I hope you can find out what's going on.