My mother doesn't want to use lights at home, I think because she thinks someone can see her, so we live in complete darkness. The room is only lit by light from TV or PC.
There is also an issue with certain locations in our apartment, where she can't go. She doesn't want to go near windows, and one of these places is bathroom. She can visit bathroom only once per day, when she wakes up, which is enough to take a shower, but when she needs to use bathroom during the day, she doesn't. She urinates into a bottle in a kitchen and then use sink to get rid of it. It is worse with defecating, rarely she visits bathroom during the day, other times she does it in kitchen, then pack it up in paper and throws in trash. But this is also rare since she can visit bathroom when she wakes up.
The last major issue is with new things in our apartment. Whenever we buy something new, be it for us, or gift for her which she wanted, it can't be in her presence, until she accustomes to it. This is usually never so we end up putting the thing in away or selling it.
Does anyone have such issues? What could it be and how to deal with it?
Your mother is showing signs of very, very serious psychiatric (and/or possibly neurological, given the balance issues and finding light uncomfortable too) illness. You need to get her help. She's a bit young for dementia but it isn't impossible - and this terrible fear she's experiencing hasn't come from nowhere.
Don't ask her permission, just consult a doctor yourself and take his advice. Tell him exactly what you've told us.
Grit your teeth, because you may need to do things your mother won't like in order to help her. But that's still better than letting her go on like this. Please do it as soon as you can, and please let us know how you're getting on. Good luck.
In any event, this is not a normal or health way for any of you to live, your mother needs help. If you feel it would be somehow disloyal to report her (probable) mental illness then consider that she could be better with treatment and it could give her the possibility of a happier and more normal life.
Could you get a bedside commode and put it in her bedroom? It would be better to empty that than her current practices.
How long have you been living together? How long have these behaviors been going on?
Sorry for all the questions, but a better picture would help us give better answers.
How do you like living where urine is dumped in the kitchen sink, where someone poops in the kitchen? Where the light is always dim? These are not normal conditions for a young person to have to cope with. So ... why don't you move out? What is keeping you tied to this dysfunctional situation?
I'm guessing that one big reason is that you love your mother and/or you feel a duty to take care of her, and you are afraid she will be worse off alone. Is that right? That is a perfectly understandable motive. But is it really best for your mother? How would she be worse off if you weren't there? It is very definitely not best for you. You are as worthy as your mother, and your happiness is as valuable as hers.
Maybe part of the reason is that you'd feel terribly guilty for leaving your mother. But the normal order of life is that children grow up and go out on their own. At twenty-five you need to do that. Surely you don't feel comfortable having friends into the apartment you share with Mom? But building friendships and long-term relationships is what you are supposed to be doing at this point in your life. Going out on your own is not something to feel guilty about!
Your mother has mental health issues. This is not her fault. I'm not suggesting that you move out to punish her. But it is not your fault, either. She needs appropriate treatment but that isn't happening, because she refuses. If you cannot help her, at least help yourself.
Bedside commode would be a new object so she would not like it. Besides that, we share the same room so there is no more space for new things.
We live together since I was born, that's for 25 years, and this behaviour lasts for about 5 years. She is 65.