Sorry it's taken so long. Everybody's been a bit out it for the winter. My pool's been frozen for a couple of months now (that's good..makes spring opening easier).
First things first.
1) Your FC is 'way too low. With a too-high CYA of 110, you need to keep your FC at 8-15 ppm routinely, unless you have an SWG. If you do, the numbers are different. If you need to shock raise it to 25ppm. They are too low. Otherwise consider draining half your water and refilling to get CYA down to 55 or 60ppm--much easier to maintain. Check the "Best Guess" table on one of the threads or at our sister site Poolsolutions.com.
2) pH can vary widely. The 2006 should have reagent 0014 with neutralizes chlorine...high chlorine makes pH appear higher than it actually is. Generally, with a vinyl liner, 7.2-7.4 is a good for spring cleanup as chlorine is more effective at lower pH but pH isn't low enough to damage your liner. Also, if you have things like fountains and water falls, they raise pH (aeration of water drives pH up).
3) since the recommended T/A range is normally 80-125ppm, why would you add baking soda to increase it when it's 110ppm????? Frequently, when people have the pH constantly rising we have them LOWER T/A to 60-80ppm and that helps. Please see our ways to LOWER T/A. Get it down to 80ppm for starters and see if that reduces your acid demand.
4) See #1. You have (probably) algae and with your high CYA levels you're not getting enough chlorine in to fight it and it keeps depleting the FC and growing again. This is an extremely common problem. You must raise FC to 25 and keep at that level, checking and adjusting 2 to 3 times a day till FC stops dropping for 24 and your algae is dead. Then you can slowly let FC drop (it will) and maintain at the 8-15ppm level.
5) No.
Let us know.
Carl