Let me start by saying I am 35 years old and just started pursuing my physics degree last year. I will be in my 40s by the time I finish my doctorate. So, you will have to excuse me if hearing a 20 year old say they are too old made me roll my eyes. You are still a kid, which is great. You have plenty of time, so no worries there.
Now, moving onto your comment about what others have accomplished by your age. I'm going to go ahead and pull away the curtain to show you what is behind most of those child prodigy stories. In most cases, the parents have their masters or doctorates, started the projects for their children themselves (or in some cases, did almost the entire project FOR them), and allowed their child to get the credit for scholarships, recognition, etc. Go ahead and look into the families behind those stories yourself. You will find this to often be the case.
In addition, when someone has accomplished something newsworthy, the media loves to embellish. Take me for example. Sure, I have studied the sciences off and on since I was a kid, but I never did anything spectacular in regards to any experiments, discoveries, etc. However, if I wanted to divulge my past to make myself more appealing to the press, I have plenty of stories to tell. I experimented with household chemicals frequently, inadvertently creating chemical bombs, toxic fumes that filled my entire house (and friends houses at times). I created various pyrotechnics, multiple versions of napalm, and experimented with many other exothermic reactions as well. I took apart just about every electronic device I had as a child, just to see how they worked. Now, giving information like this to the media, a good writer could easily turn this into an amazing story of a child prodigy who turned his household and the households of his childhood friends into his own personal laboratories. The fact is, it is all a matter of perspective and how you tell the story.
Yes, there are a very select few who accomplish amazing things without an adult doing most of the work for them. However, they are few and far between. In addition, there are more of those child prodigies who end up fading out of the spotlight later on in life than those who you hear about in the decades to come. On the other hand, there are some individuals who accomplished very little in their earlier years who end up accomplishing amazing things later on in life.
As far as the panic attacks, it seems to me like you are just stressing yourself out way too much over all of this. You need to take a step back and breathe. Figure out what you need to do in order to figure things out. Stop trying to push through college courses to do so and start trying to figure yourself out. Maybe try some personality or career tests to help refine what your strengths and interests are. Look into some specific professions, maybe volunteer at some facilities that have the professions you are considering. Take some time to see the fields firsthand. If you need to take some time off from college in order to do so, finding yourself will be far more beneficial than just trying to plow through courses in hopes that you will figure it out that way.
You are still so young. You have plenty of time to find yourself. More often than not, the most brilliant minds have a hard time figuring out what to do with themselves because it is hard to keep their attention. They learn fast, then move onto the next interest. Someone who is brilliant and knows exactly what they want to do as a child is an exceptionally rare find, and in no way guarantees that they will do any better than someone who figures it out later in life.
I wish you luck and hope you find what you are looking for soon. Just remember, you are doing this for you. Not your parents, not your teachers, but for you.