Well, hopefully, you have a glucose meter at home with test strips (or whatever) you can use to monitor your fasting blood sugar levels. It's fairly easy to find normal values online for what a fasting blood sugar should be. If they are abnormal, it's definitely something you want to bring up with your doctor. Apples are supposed to be good for helping to control your blood sugar level I've read and cinnamon can have an affect too, so you might want to talk to your doctor to see if you should try both or either of these things to help if you have high blood sugar levels.
Getting a copy of your medical records is a great idea! If you can organize them in a folder, they can be pretty easy to lay your hands on when you are planning to visit a doctor... you can have them at your fingertips anywhere you go. You'll want to make sure if they look at them you get your copies back so you don't have to start over in getting more copies, which I imagine might cost some money?
If you don't have one already, please buy a blood pressure monitor from the store. The instructions on them are quite simple and you can learn if you are having high blood pressure readings frequently or not at home that way. Hypertension is definitely something to watch for if you have a lowered glomerular filtration rate (GFR) with your one kidney. Also, if you do, avoiding NSAIDs such as ibuprofen I believe is generally advised too (have a sibling with two kidneys, but one is congenitally defective)- you probably already know that about NSAIDs.
There is a way you can do the "poor man's tilt table" test at home. Use a blood pressure cuff that also takes your pulse. Omron is generally a good brand if you can get one of those.
Take your pulse or have someone do it that knows how- that's in case the monitor gets the pulse wrong (sometimes they seem better for the blood pressure than the pulse reading). Lay down for about ten minutes. Take your blood pressure and pulse with the monitor & then take your pulse in your wrist. Then stand up. Wait a full minute and take your pulse, etc. again. If your pulse is more than 30 beats a minute faster standing than it is when you are lying down, you might even remain standing and take it again after you've been standing five minutes. Record the numbers and show them to your doctor you and ask if you could be referred to an electrophysiologist for a REAL tilt table test. Another test that might be done to confirm P.O.T.S. is a standing plasma norepinephrine test.
If you learn you have any form of dysautonomia, including if you have P.O.T.S., as I do, feel free to join the dysautonomia forum here on medhelp and ask questions! Here's a link: