Increase dosage, try new meds, or new doc | ADHD Information

I have written this before, so sorry to rehash for those who are sick of hearing me say it. I (and many others) have the same problem. Adderall XR tends to last about 8 hours in most people... not enough when you work and go to school. I take 30mgXR in the morning and 10mg regular Adderall at 4:00 or 5:00 in the evening to get me through evening studying. Doc writes me out a script for 60 5mg tablets, 1 or 2 as needed. If your doc is not comfortable raising your dose, could you go back to 20mg XR with 10mg regular in the afternoon? It would be the same total daily dose you're taking now (30mg), just divided up differently, so I see no reason why he wouldn't agree. Technically the max dose in adults is 30mg, and the recommended dose is 20mg. My doc caps me off at 40mg mainly because I was started on regular Adderall 20mg twice daily when I was diagnosed at 17, before XR hit the market. Since I have always been on 40mg, he's never tried to lower it.Back in August, at 26 years of age, I was diagnosed with ADD and placed on 20mg of Adderall XR and have been recently increased to 30mg - I think it's working ok, concentration could be better, but my main concern is that the medication wears off around 5-6pm and I'm usually very tired and unfocused and unmotivated afterwards, which is bad because this is the time I need to study and get homework done - I'm still trying to struggle through college.  My doctor seemed somewhat concerned with upping my dosage to 30mg and basically told me that I should maybe consider trying another medication or just take my medication when I need to study later in the day and sacrifice being able to concentrate at work and in class for study time later....this doesn't seem like an acceptable trade off to me and I'm not all that comfortable with talking with my doctor(and have already thought about switching) - can anyone else offer suggestions or experiences? Should I have to just deal with not being able to focus at some points of my day? How much Adderall is too much? I'm really lost and I don't even have any resources for ADD coaching or anything in my area.....not that I could even afford it if I found someone....but any reply would be appreciated!