Advice/Encouragement/Tips? Anything helps! Bombing the second half.

My best score is 162 but I'm not scoring that consistently. I have a major issue with stamina. The longer the test goes on the worse I become. To be fair during section 4 someone at library started talking near me which threw me off completely for the rest of the section but this is a pattern for me. How do I keep my accuracy up as the tests progress??? I am not improving and its been about two months that I've been studying daily and PTing weekly. Any insight or tips appreciated because i feel like a failure.