Short answer:
Yes, it seems normal.
Long answer:
Here's a chart which you can use to roughly determine your state of charge:
Assuming that the voltages you measured were with the battery at rest (no current into or out of the battery, including the inverter) you were charging to 80 to 100% charge. So far, so good, your charging system is mostly to fully charging your batteries with the generator.
In the AM the measurements are saying you discharged to about 15 to 30%. Not terrible, but your batteries will have a significantly lower life if you discharge them below 50%.
Your batteries have approximately 220AH capacity, so you were using 110 to 187AH.
Your inverter will draw maybe 2AH for every hour you leave it on (the standby circuits that light the red pilot lights on your TV's do take some power). Your CPAP draws 10 to 15AH for every hour you use it.
Assuming you have the CPAP on 8 hours an evening and the inverter on the same or more, your taking 102 to 144AH just to run the CPAP machine with the inverter. The fridge uses 1AH every hour as well, so that would be another 21-23 AH with running the generator 2-3 hours per day, for a total of 123 to 167AH. Not too far from the 110 to 187AH calculated above.
I agree with Mel that the 2 6V batteries are marginal powering a CPAP from the inverter. My wife's CPAP runs off 120VAC and 12VDC also, we bought the 12V DC cord from a medical supply house for approximately $30.
These numbers are just guesses, if you really want to know what you are drawing I'd highly suggest installing a
TriMetric or equivalent Energy Meter, which will tell you exactly what you're putting into and taking out of your batteries.
I obtained the chart above from
The 12V Side of Life, a resource I'd highly recommend reading.