The doctor should be prescribing the proper number of pills for you, to last you until your next visit when you get another prescription It is important to keep your regularly scheduled appointments and discuss your dosaging with the doctor.
How often do you see the doctor and how many pills does he prescribe for you? How many do you take each night?
If you have any difficulty sleeping, as you are, then you must talk to the doctor about it because this can be a side effect of the medication. You should not miss any doses.
The seroquel helps to settle you down and it helps you to sleep. When you don't take it for 3-5 days, then you don't have your usual help to fall asleep and that is the reason for your sleeplessness. You can help yourself to sleep at night by doing relaxing activities, but I don't kno that this will work for you. The doctor needs to adjust the prescription so that you can have medication every night. You are on a very high dosage, so ask the doctor if the dosage can reduce slightly so that you have enough medication for every night.
I hope this helps you!