I dont think that you have a disorder or anything, at least not in my opinion. Sometimes we do need our own private space. If your in the city and people are always around, then it just might be that you need some quiet time to yourself. The lonliness can come from when you are with others and need to perform and thus you are giving too much of yourself and maybe you just want some personal space.

Maybe you are at a point where you think you have to socialize and if you don't then something is wrong with you. Maybe you just need a break and you just want to take time out, that can be ok. It is possible to be around others and be lonely, maybe your not personally connected and it is just a function rather than having a close personal connection with others. That can make you feel lonely and you may not understand it.

Take time out, depending on what you are doing maybe you may want to just take some classes or spend time reading and taking things in, instead of giving out to others by socializing. Or maybe you have been taking too many classes if you are in school. If you are young or in your late teens, it is not unusual to have times of feeling lonely and lost, that is normal. Often one doesn't really have a real direction when they are young, it takes time.

Just some ideas,

Open Eyes