Should I be busier during A-Levels?

Okay, this might be a little bit of a weird question, but hear me out.
I feel as though I'm not as busy as some of my friends at college, and I have no idea if this is a bad thing. I don't think it is, because I'm pretty happy with the amount of stuff that I do, but all the same, I guess I don't want to be wasting my time if it's going to disadvantage me in the future.
This is pretty much all I do at the moment:
- A levels (obviously)
- Violin
- Spanish (outside of college)
- Hang around with friends every now and again
- Swimming
- Extra reading around what I want to take at uni (which is French+Russian)
- Watch YouTube in my free time
I don't really revise for stuff like others do, I just do as much as I have to in order to get As (I'm doing AS this year). I have a friend who revises like 5 hours a day, and another who does volunteering and a part time job.
They always seem busier than me, and I can't relate to the stress. I feel as if I'm missing out on the experience, haha.
Basically, should I be doing more stuff? I want to go to a fairly decent uni, but I'm unsure of anything useful I could do that would be relevant to languages. I mean, I'm planning on helping out with French at the local primary later on in the year when I've finished up with college but that's hardly substantial. At the moment, I only have my wider reading (L'Étranger, etc.) that's actually of any use.
Any advice?

You're doing fine.

I couldn't relate to much of the A-Level stress either, but I suppose it's different to everyone.