The sleep clinic may be able to help some, but you need to read a book on sleep issues because any resolution will come from what you can do. You need to go to bed at the same time each night and get out of bed after 15 minutes if you wake up in the night until you are tired enough to go back to bed and sleep again. Measure how much sleep you get on average after a week, then figure what time you want to be up at so you can start the program. Go to sleep 15 minutes earlier than your average sleep time subtracted from your wake time.
So if you want up at 6AM and average 6 hours, go to sleep at 11:45 for the first week. Gradually increase the bed time by 15 minutes each week until you are sleeping the target hours you want. i.e. If you want 8 hours of sleep, go to bed at 11:45 the first week, 11:30 the next and so on. If you don't sleep enough in one night,do not linger in bed in the morning, just get up and you will surprisingly be able to work - and you will be more willing to go to sleep the next night because you will get tired at night. So it takes dedication to develop a sleep cycle, which you are not doing at all now because you are like I was - thinking your body was figuring the best time to go to sleep.
Don't listen to music, or tv or anything in your bed during the time allotted for sleep. If successful, you will develop a rhythm that works.
You're doing the right thing getting tested, as you want to either treat or eliminate the possibility of OSA, which can cause the symptoms you describe.
Presuming you have no underlying medical conditions causing this, then my take is this could be a circadian issue. Meaning you no longer have two sharply defined rest-awakened periods, but they are overlapping.
One solution would be to completely ditch the naps. Avoid sleeping in. Only allow the minimum time in bed you normally need for sleep. Then give this schedule several weeks to see how you adjust.
Will be interesting to see what your sleep doc says, keep us posted.