Wow, first off, thank you all so much! I wish I could respond to all of you individually, but that would be a little unreasonable... And I'm sorry for not responding for so long, it's my first finals week as a College student!
To clear up a few things:
I don't need to spend money on food or housing because I'm 18, a Freshman in college (switching from Biology my first semester to Mechanical Engineering next semester), and my awesome parents are paying for college. So I'm not necessarily planning on making photography a full-time job, but I would love for it to be a side job in the future and as a way of making some fun money right now.
Again, thank you all so much. I read all of the responses, and I'll try to answer most of them in this.
I will probably stop using Google AdWords now, but I will say that two of the jobs that I have gotten just this month were through it. However, I'll probably focus more on word of mouth now.
I am not sure whether or not I'm going to take classes. A teacher of mine from high school is also a professional photographer and he has been helping me out a lot (I'm actually going to see him on Friday to talk about photography stuff), so I'll probably ask him if I can tag along for a wedding or something similar to get some pointers. I will probably join my local photo club, however, as it is really cheap.
Now for the money: I will probably upgrade in roughly this order:
Spare batteries ($27)
Used Pentax K-50 ($300) or used K-3 ($550)
Extra flash for the extra body ($40 new; I know that's cheap, but I like the flash I have. Link:
https://www.amazon.com/Neewer-Display-Speedlite-Cameras-Standard/dp/B010XCEA...ewer+speedlite)
Sigma 17-50 f2.8 ($400 new, quieter AF than Tamron)
DA*50-135 f2.8 ($550 used)
Things I want to work in at some point:
Pentax 50mm f/1.8 ($100)
New camera bag that can hold two bodies, flashes, and lenses ($???)
Again, thank you all so much for your input. If you have any comments on my current plans, please let me know!
Robert