First you have to be honest yourself getting a 165 or 170 is unlikely. That puts you in the top 10% of test takers and people that take the LSAT in the first place are college graduates who are motivated enough to attend law school, which puts you in about the top 1-2% of people and 98% of us myself included did not get a 165-170 on their LSAT.
On top of that if you got a 149 on your diagnostic it probably means you won't score that high. With that said you if you show up and take the test you can likely get into an ABA law school and I will tell you only 5% of lawyers nationwide attended top 10 schools. There are 200 ABA law schools and only 10 in the top 10. This means 95% of lawyers nationwide did not attend Harvard, Yale, Stanford etc. I myself didn't, but am a lawyer and love my job. I also work with many other lawyers most of whom did not attend top 10 schools a few Berkley grads, but we are all licensed by the state bar to practice law and work in the same office.
On top of that what is really going to change in a few months? You have been prepping with Kaplan for months if you were saying you hadn't done anything to prepare then you should probably wait, but it sounds like you have been studying. In a few months you will feel the same panic and being unprepared. When you go to law school you will completely unprepared for finals every time and then when teh bar comes my god you will feel unprepared. Then when your a lawyer you will never feel fully prepared for a trial and that feeling of not being 100% ready is part of being a lawyer.
With that said it is your decision, but I am willing to bet if you wait until the October test this same feeling will come up. If you have taken courses and put in a good faith effort take your test and get a score then know your options. Also do not be disappointed if you don't get a 170 almost nobody does.
You will also need to be prepared for that realization when you attend law school in the same way only 10% of test takers can score 170 only 10% of any law school class can graduate in the top 10%, but on your first day 100% of law students who are the same people you are competing with on the LSAT are smart, motivate, and hard working and truly believe they will be in the top 10%, but 90% of those people are wrong and half of them finish in the bottom half of the class.
Bottom line I recommend taking the test you have taken the course and studied for months. There is not much more you can do, but if you truly believe you are not ready it is your call, but I don't think anyone that has ever taken the LSAT felt confident going in, but once it is done it will be a relief. The same feeling will be present throughout your law school career, the bar exam, and your career as a lawyer.
Good luck whatever you do.