Look, I'll be blunt, so sorry if I hurt your feelings.
First, let me make a few assumptions (correct me if I'm wrong). I assume you are a man and you like women. I also assume that you are smart because you have a great education, IT experience, and you managed to make a ton of money: $1.5 mil by age 37. I also assume you are average looking but a little out of shape (you mentioned gaining weight).
A little bit about me. I am about the same age, also live in the US, though I grew up overseas. I lived in other countries and traveled a lot internationally. My net worth is much smaller than yours though. Like you, I have spent pretty much all my adult life either studying or working. This includes working for a number of asshole bosses.
First of all, congratulations. You made it. You never ever have to work for money if you play your cards right. It doesn't mean you should never work but you don't have to. I wish I were in your shoes. Even with a fraction of your net worth, I am considering semi-retirement in the near future. You are in a much better position though.
Most of the problems you have are in your head.
A few points.
You had a health scare. I also had a few. Life is short. Life as a healthy and relatively young person is much shorter. If anythihg, the health scare should help you change your life. Which brings me to my next point.
You seem to worry too much about what other people think and how they see you. For example, when they see you somewhere during the day not working. Are you kidding me? Again, you have more than enough money to do whatever you want. Why the fuck do you care what other people think?
You are paying your parents $1700 per month for room and board. Do you know how many places are in the world where you can live pretty well on even less than that? Using a 3% withdrawal rate which is pretty much bulletproof, you can spend $45K per year and never run out of money unless there is WW3 or something. Even in the US, this is enough to live pretty comfortably, but the world is bigger than that. There are many places where you can live like a baller.
Here is my advice to you. It seems like you have too much baggage from working for shitty bosses, living with your parents, staying in the same city for too long, etc. You need to detox, to reset you mind.
I assume you like women. Any particular type? Eastern European, Latin American, Asian? The US is a great country and I am very privileged to live here and become a naturalized citizen, but let me tell you, it kind of sucks for dating if you are an average looking single man in your mid 30s or older. There are many other countries where women will be a lot more interested in you unless you are hideous (I assume you aren't). Many of those countries/cities also offer much lower cost of living vs the US, great healthcare, reasonably good safety and many other advantages. Ask me about specifics if you are interested and I'll send you a PM. I don't think this is the right forum to discuss the specifics, but one thing I'll mention here is that I am not talking about hookers or gold diggers, just regular girls. Unlike in the US, those girls would rather date you, a smart and serious IT guy who has his shit together, than some random dude from Tinder with a heap of muscles, a bunch of cool tattoos and a negative net worth.
So, back to the idea of resetting your mind. Is it just about getting laid? Of course not, but that will definitely help to clear your head and put you on the right path. That and seeing the world, eating clean, exercising, staying healthy, meeting new people from all walks of life including free spirits from the US who may be much poorer than you or even I, but much happier nevertheless.
After a few months of traveling around the world, meeting new people and having fun, you can figure out what to do with your life. A few ideas: work for a charity helping poor people for free, create an IT startup, build a website or blog, teach English or something else, work as freelancer, write books, compose music, just travel around for and do nothing for a few more years, the list goes on.
Regarding taxes and selling your stocks: just find a good accountant. You can afford it.
This is just a general idea. Feel free to ask me about any details and additional information sources.