With a CYA of 30, you'll need to KEEP your FC at 12 until you complete the shock PROCESS, which you do by passing all of these tests:
1. CC of .5 or less (your new test kit will help with this)
2. Less than 1 ppm lost FC overnight (see Overnight Chlorine Loss Test in Pool School)
3. Your water is clear
Until those three things happen, you need to test as frequently as possible (hourly in the beginning) and re-dose with liquid chlorine (bleach) to get back to shock level of 12 FC as soon as it dips below that number. The more you test and re-dose in the beginning, the more efficient (quicker and cheaper) you'll complete the shock process and start enjoying a trouble free pool. One note: before fully embarking on the shock process, test everything when you get your new test kit just in case any of those numbers are off by a lot. You'll want to address pH first (if it is really is 7.5 I think that is okay, but if it is too high or too low, fix it first). Also, you'll want to ensure your CYA is really 30 because when it comes to the shock process, knowing what your FC level should be is dependent on that CYA number.
Good luck and post back as needed.