Given the amount of effort you have put in, seeing your grade improving only two points should have been very disappointing and demoralizing. If you think you are truly happy with your score, then there is no reason not to move on. Although there may be people who truly enjoy studying LSAT, but normally, studying for standardized tests is not a pleasant experience and should be kept as short as possible in my opinion.

On the other hand, since you identify yourself as an overachiever, I would like to tell you that nothing is impossible, if you have a will to do. I've been working at a tech startup full time for three years since my graduation. Normally I work from 9 to 7, but during the crunch time, I work nearly 55-60 hours a week. I initially thought that it would not be possible to dedicate much time in studying for LSAT. But since I began preparing for this test in January, I have been able to study 4 hours on every weekday consistently. It is very tiring indeed, but it was possible. When I first took my diagnostic in January, I got around 160, untimed. My RC was a total disaster. Now, I am consistently getting 175+ on timed PTs, and I think the pain I had to go through was worth it. And I believe, you will feel the same.

Whatever your decision is, I wish you will be happy with it. Great job on your hard work, and if you can, keep pushing yourself!