Kaede

A massive thank you to everyone for your input. All of your replies prompted much-needed self-reflection as to where my anxiety was coming from.
Regarding anxiety: I know I want a Ph.D. My anxiety stems mostly from the fact that I am unsure which field to pursue a Ph.D in, and secondarily that I am unsure what I would like in a supervisor.
I started feeling anxious when I was looking at the departments of schools. I know people recommend you read papers to get a good idea of who is leading the fields, but they also say you should only apply to schools where you like at least 3 of the PIs, so I was trying to find a good 'fit.' I quickly amassed a list of 60 school/departments that I cut down to 10 schools based on my familiarity with research. So much research doesn't sound interesting to me simply because i haven't been exposed to it, but once I do it becomes fascinating. What if I am ruling out a subject I would adore simply because I haven't taken a class in it?
Now, my list is mostly prestigious, crap-shoot schools with departments all across the board: genetics, neuroscience, physiology, cell biology, "biosciences," etc. I just can't help but feel that I am doing this incorrectly. Considering I've only ever done research in physiology (and it was OK, though I feel it is not the field I was destined to be in) and little if any genetics/neuro work, I am not even sure how I am supposed to tailor my SoPs to these prestigious programs. I think @knp said it best: I am feeling very fuzzy.
I'm trying to remedy this by applying to schools with interdisciplinary departments and rotations, but you still have to apply to one department.
And then, on top of ruling schools out based on interest, worrying about whether a supervisor will be a good fit or even have enough funding...
I'll be applying to postbac programs as well, but most of these programs are for students who aren't competitive. And I don't mean to toot my own horn, but I feel that I may be a bit too competitive for the programs because of my awards. And if I end up applying to a postbac and getting in, wouldn't it be better to apply to graduate school then?
All these thoughts are very anxiety inducing!
Of course! Otherwise I wouldn't be applying. I'm just unsure as to whether I've had the diversity of experiences necessary to really know what I'd like in a supervisor or in a lab.
This is exactly how I feel, though I suppose if I did a postbac I wouldn't exactly be leaving academia. You're right about the time issue though - I definitely wouldn't want to spend more than a year off.  Looking back, how do you feel about your decision?
You're right, I hadn't thought about that. Thank you for your perspective. I hope all goes well with your decisions as well.
Your post really hit the nail on the head and made me realize that the lack of clarity is what I was missing. Despite that, professors and mentors are saying I'm competitive enough. I just can't help but feel that they're wrong, or that I'll end up in the wrong place.
It sounds like you were happy about your decision to take a gap year. How did you navigate asking them for letters of recs from 2 or 3 fields, even after the clarity you received from a gap year?
Thank you for this post - I really needed to understand why people were telling me to apply now. Unfortunately I can't reduce my coursework since I will not be able to graduate on time if I did so, so my plan would be to figure out which schools/departments to apply to by the end of the summer, which is also contributing to anxiety. What do you suggest with regards to applying to so many different departments because of the fact that I have no idea which field I'd like to go into? Thank you again.

Haha. No. They accept less than 40 people each cohort. You have no idea what you are talking about. Go back and crawl in your hole, no one needs your opinion.

People put considerable time and effort into giving advice, whether you think they did or not. They took time to type something they thought you would find helpful. Calling them out for not saying what you want makes people less likely to give you constructive advice. How would you feel if you took the time to read 6 pages, gave your thoughts, and then OP basically told you it was useless??

It's similar to lab stuff. You slave over some data, hand it to your PI, and then they go "haha, this is awful!" It's not a good feeling and makes the person less likely to put that much time in again.

You've also named some professors by name, so you could reasonably be identified by someone. What you post on the Internet can and will come back to haunt you. Being rude to people on the Internet is the same as in real life.

/end rant

You need to drill down on why you are anxious about continuing your education. If you do not want to be in school anymore, then don't do it! Grad school is not like undergrad. You have to be very self-motivated to complete it, and if you're not, then it is hell.
However, if you are just nervous about the application process, then that is very common. Gather more information on what you want to do and go for it. You do not know how well you will do until you try. Michael Jordan once said "You miss 100% of the shots you don't take."