Why am I always so tired? I am always bone deep exhausted. I could sleep 20 hours a day and still be tired. I'm on lamictal and cymbalta (duloxetine).

Tell your doctor. Fatigue & exhaustion can be due to your medication, either as a side effect or from too much! Or perhaps you're anemic or hypothyroid. If you're getting enough sleep (20hrs is plenty!) and still tired, perhaps you're not getting good quality sleep. In other words, you might have sleep apnea. Regardless, you need to talk to your family physician and get diagnosed in order to get properly treated.
Talk 2 psychiatrist. If this started since you've been on these meds then maybe the dose is too high or not right for you. If a change in meds doesn't fix the problem, then get a complete med eval, as there are several conditions that cause severe fatigue.