Before you decide what you should do this time, I think you need to honestly assess what you did last time and which parts worked and which ones didn't. Your scores look like they peaked in the middle, like you said, but there is also the randomness factor of which MCAT you get. With a range of 24-30, it looks like luck didn't work in your favor that sitting. It might next time, although you can't count on that.
Looking at your AAMC scores (being that they are statistically the most valid predictors of the actual MCAT) you did the following in each of the sections:
PS: 9, 10, 11, 10, 10, 11, 10, 9 for an avg of 10 -- real test = 10
VR: 9, 10, 10, 7, 8, 7, 8, 7 for an avg of 8.25 -- real test = 6
BS: 8, 10, 9, 9, 7, 9, 8, 9 for an avg of 8.63 -- real test = 8
For PS, two things look to be true. (1) You did your mean. On a different day you might have gotten a 9 or an 11. (2) You didn't improve over the course of your preparation. That's usually a sign of someone who studies the material intensely but doesn't master the nuances of how to take the exam. You have to honestly answer for yourself whether you mastered the art of POE and whether you relied more on common sense or memorized information when you took the MCAT.
For VR, it looks like you lost your mojo about half way through and never got it back. You were doing fine in the beginning and then suddenly dropped at that fourth AAMC test. Because the scores stayed consistently low after that, it would seem like you made a change that didn't work for you. I think you need to go back to whatever approach you had in the beginning of your studies, even if that means no real strategy besides just reading passages and answering questions.
For BS, you did within the range of your mean. On a different day with a different test you could have been a 9 or 10. I think you need to go back and see what subjects on AAMC 5 caused you trouble and recall whether those were on your actual MCAT. For BS, it could be as simple as emphasizing the areas you struggled at your first time and glossing over your areas of strength.
No matter what, you need to start by analyzing what led to each of your subscores. There is no way you'll improve beyond your range (24-30) if you don't first identify where you were weak on your first sitting.
1. My scores basically peaked in the middle and decreased more and more until I got my lowest score on actual test day. I am wondering if it is possible that I overstudied. What do you think about a less intense study plan the second time around? What is a good length of time to study for the test?
Over studied? No! Studied incorrectly without transitioning from absorbing information to learning to take the exam efficiently and confidently? Yes. Forget labeling it as more intense or less intense. Instead, give yourself more time this go-around to completely go over each and every answer explanation, emphasizing which choices could be eliminated, which are distractors, and which are tempting choices that don't quite answer the question. Recognizing what not to pick is just as important as knowing what to pick.
2. I made notecards of every question I missed (so I would get a similar question right if asked again... only did this only PS and BS). I also made notecards for every topic I was unfamilar with. I probably have 1000+ notecards. Do you think I should review the notecards the second time around?
The ones on the questions for sure. But define what you mean by review. Reading them a few times over until they stick in your head? No! Rewriting those questions and answer choices to practice with at a future date? Yes!
Emphasize the thinking not the knowing.
3. Which test prep company would you recommed that I use? I was thinking exam krackers would be best based on what I've read on other discussions, but I am open to other suggestions.
I'll pass on this one for reasons of etiquette. The only thing I'd emphasize is that you need to first decide whether it's information or test strategies you want to prioritize this time around. If it's information, go with the one that you absorb best from. If it's strategies, go with the one with the best answer explanations.
4. Lastly and maybe most importantly, which practice tests should I use? Unfortuately, I have already taken all of the AAMCs and most of the Kaplan FLs. Is it a bad idea to retake these tests/Will this give me an accurate score?
Repeating is an option, but you can't take the scores seriously. Redoing AAMC exams to see patterns in their answer choices is an excellent way to improve your test skills. But because you've seen the answers to those questions already, they can't simulate the real exam for you. When it comes to fresh CBTs, you're pretty much down to either BR or GS. Do a search and see what people think.