I have always had a sweet tooth, and eat a lot of sugar foods in my day. I am a female, 5' 2'', and 21 years old. I have a BMI of 24.8 which is still in the "normal" range but any higher would be considered overweight.
I do not eat many vegetables, eat mostly things like soups and noodles, only eat meats like chicken, tuna, and beef, along with various sweets. Always been a chocaholic, and I must admit very often I'd make chocolate frosting just to eat it. I don't exercise, am inactive, and drink lots of water. The sweeth tooth seems to be genetic, as my grandmother once made a cake for her kids afterschool when my mother was young and she ate the whole thing before they got home.

She was the same body type as me, not overweight, but not exactly a healthy weight either.
For the past year or so my periods have slowed and became very infrequent. Recently when I eat something, especially something sweet, I will feel a dull, achy, burning pain in my stomach, but mostly in my back behind my stomach. Because of this I have begun to fast and am going to try to eat more vegetables and fruits along with things high in fiber like oatmeal. The pain at times was pretty intense and I had to lay down. Also, when eating foods I have gotten moments of intense heat that almost make me sweat and make me feel very uncomfortable. I have not gone to the doctor about my menstruation but it has been worrying me, my mother says not to worry because it can happen in young people from time to time, but I feel I'm a little too old to have that still happen.
I am worried I am getting prediabetes or have it, and am wondering any tips on reversal or if these are known to be common symptoms of prediabetes. These symptoms are very new, within the week, other than my missed periods.
Thanks in advance.