Hmm... "Dot.Calm" gave *some* decent advice, BUT...
If you really want to be sure, see a doctor and set up an appointment to have a real fasting blood sugar test... and by fasting that means at least 8 hours with no food, though water and your usual meds are generally ok (again, ask the doctor setting up the lab tests)... Even if the doc initially tries to say you don't need the test, tell him/her you are worried about it given your past experience and results and he/she should ok it.
Otherwise, as general advice (and I am NOT a medical doctor) I can only tell you that in my personal experience as a Type 2 Diabetic, that increasing your physical activity (and it does NOT have to painful exercise, just increasing your physical activity... walking, etc) and paying attention to your diet and nutrition can work wonders. For me, increasing my fiber intake has worked wonders, as well as paying attention to the amount of sugar/"bad" carbs, and fat that I eat... stay physically active, eat more fiber, pay attention to what you eat, and consult with a medical doctor and, if you can, a nutritionist/dietician.
I hope you feel better soon.
"Am I becoming diabetic?"
Answer is no, but then anyone not paying attention to their sugar intake and/or diet can become a diabetic. Right?
Is a fasting glucose level of 104 pre-diabetic? Depends on who you talk to and what site you read on the net. Some say 110-120 and others say 100 -120. If you can keep it below 104 you will be alright in the short term. Short term because it is now that you need to carefully monitor your sugar intake and start to reduce it. Eating "...a huge meal of pizza and mountain dew" is not it. Read food labels and avoid foods with excess sugar, including carb sugar. Some bread mfg stuff excess sugar in the flour to gain "taste".
As far as when to test glucose that depends on what you want to see. Two hours after eating blood sugar is around its highest level but that depends on the food and drink you have consumed. Sometimes its up to 4 hours. Normally a 122 reading after eating isn't something to fret about. And be sure to calibrate your glucose meter every three months. I use LifeScan and they supply me with the test fluid for free. Send them an email it will save you $8 or so.
You're at a good weight level. Keep it there. Moderate exercise helps to reduce blood glucose levels. Walking is very good not only for lowering glucose but also for the heart and overall well being. Hey, just a quick 1/4 mile walk does wonders.
Cymbalta (Duloxetine) has hard side effects including what you posted. See this http://tinyurl.com/2h4ezv for all them and what meds to avoid.
Its good that you're concerned about diabetes but do not go overboard worrying if you can control your diet. If pounding down half a chocolate cake with diet soda nightly is your gig then you have issues.