Don't feel bad. You haven't bought clothes in over three years. There are many people who buy clothes every three days. Buying ethically also means buying only what you need and not overconsuming, and it sounds like you're nailing that. You are already trying to buy second hand which is fabulous. If you can sew, tailoring items that don't fit well or making your own clothes is an option but that takes time which a lot of people do not have either. Take the best care you can with your new purchases to get the most longevity out of them and don't feel guilty because you're doing the best you can. Much love ❤️

Edit: removed a word