I hate to say this, but this is completely and 100% dependent on you and what your priorities are. The list of things you said really don't seem like all that much to be honest. Your collection is only going to get bigger if you continue the hobby. What is the cause of your claustrophoia, is it because the things you have are take up a lot of space relative to what space you have, or are you feeling suffocated by the stuff itself, thats a big difference in terms of what you do to deal with this long term.
You have to figure out what is your motivation, why are you starting to amass things? If you want to be a minimalist, make a list of all the things you absolutely must be able to do, figure out what you need for that, then get of what you really don't need. In some cases you might to able to go out and get something else for the sake of getting rid of two things if that is really what you want to do. On the other hand if you want to keep everything but you just don't have the space you can try some creative organizing, rent a storage unit, or maybe move into a bigger place. Whatever you do just make sure it's really what you want to do.
I'm 32 married and have 4 kids and i've been interested in computers since I got my first 486 when they were new and I was in elementary school. When I got a little into my teens I started dumpster diving and bringing all kinds of stuff home to my parents basement. Through the 90s to early 2000s I had a ton of stuff I wish I had kept, but when I moved out of my parents house at 19 I downsized trashed a few dozen towers which in today's market probably would have been worth 100 bucks a piece to the right person, but they were worthless back then. I basically downsized to 2 desktops.
Now that I am much older and have a house with a large basement and more money to spend then I did back then I found myself getting back into it and wanting to have systems to play all my old games. Several years ago I started hunting for deals. My basement now has about a dozen different monitors and 25-30 desktops and 100s of parts and that is just PC's that doesn't even include my Retro Console habit. I can't seem to pass up a single cheap or interesting deal. I seem to have a need to own every single video card ever made....