Hi Sheri, and welcome to the forum!!!!

You've done a good job in educating yourself before your pool was filled, and that has already paid off for you--you kept yourself from buying $200+ in chems from the pool store that you don't need--what we call being "pool-stored"!!!!

Since your pool was cloudy and went awhile without stabilizer, I would go ahead and shock the pool up to 15 ppm. I'm not sure what your pool volume is, but I'm assuming around 20K gallons. In a pool that size, each quart of 6% bleach will raise your FC by 1 ppm. You need to get to 15 ppm and hold it there by testing and adding whatever amount it takes to get back up to the 15--do this 2-3 times daily, or as often as you can. Leave it at 15 ppm until 1)the pool clears, 2)the CC goes to zero, and 3) you don't lose a any chlorine overnight when measuring after sundown and again before sun hits the pool in the morning. At this point you can let it drift back down to the 3-6 range and enjoy your pool.

As far aw whether to raise your CYA, that's a personal thing--I'd give it a week or so after you finish shocking the pool so you can get a feel for what your chlorine loss is going to be on a daily basis...if you're losing excessive amounts, then you can up the CYA a little and see if that helps.

You might try a paste of water and baking soda on the ring at your waterline. It won't hurt your pool chemistry and usually does a pretty good job of cleaning up vinyl liners. You may also find that after shocking the pool you don't see the ring anymore, either.

Hope this helps!!

Janet