If your CYA is 140 or higher and CH is 840, a full drain this Fall will be warranted (it's too hot to do it now).
Your FC of 5.2 is about one half of the minimum required for a CYA of 140.
Be aware, the pH test will read falsely high with FC > 10.
You may be able to limp along until mid/late September and the temps cool. But you will have to be diligent with FC and pH. As mentioned, your other option is a no drain water exchange - butchances are to get a 50%-60% reduction in CYA, you will need to exchange close to 75% or more of your pool volume.