Baking soda is not used to raise pH, it is used to raise alk. What is your alk now? 20 Mule Team Borax (laundry aisle at Walmart) is used to raise pH. Add a half a box slowly to the skimmer. Retest pH a couple hours later and add a little more if it is still below 7.6.

Did you add the rest of the CYA as advised?