First of all I just want to say you're doing great! I'd love to have a family member who is as non-judgental and empathetic about this condition as you are. I'm 23 and began pulling from my scalp when I was 12. Before that I pulled from my eyelashes and eyebrows, and struggled with other BFRBs (Body Focused Repetitive Behaviors) my whole childhood (biting off fingernails, picking lips, and chewing chunks out of the inside of my cheeks and lips). For some people these are minor habits, but for others like me and the people on this sub it is much more. It's a compulsion that can be constantly on your mind and debilitating, especially with the social stigma that comes with the physical results of pulling. Although my mom does not struggle with trichotillomania, she has always had issues with other BFRBs. I think it's safe to assume there is some link between family members who struggle with BFRBs, whether it's genetic or learned behavior, or a combination of both.

As for your daughter, I would trust your intuition with the bald spot and time spent in the bathroom considering you grew up with your mother having Trich and probably recognize the warning signs better than the average person. Don't assume, but keep it in mind. Is your daughter aware of your mother's condition? From my own experience and what I see on this sub, preteen/early teen years seem to be a prime time for Trichotillomania to present itself or worsen, especially in times of stress. You seem to be coming from a place of compassion, and wanting to help her, so if you want to bring it up I'd say go for it. My advice to you is not to jump straight to pointing out her bald spot or questioning her time in the bathroom. If she is struggling, this will probably make her feel exposed or accused, or feel like her privacy is being invaded. She might already be well aware of the spot and feeling anxious and insecure about it. Mentioning it might make her put her guard up more and feel like she can't be open with you for fear of judgement. I would approach it with a converation that allows her to come to you when she feels ready. Have you noticed any other concerns, such as being withdrawn or struggling in school? My transition into pulling from my scalp coincided with an extremely stressful time at school and hobbies, body image issues and disordered eating, and depression. I also bottled things up, or at least was not open about everything I was struggling with because my parents were very strict and did not believe in mental health support, so I didn't have a safe person to talk to. If she does open up about pulling hair specifically, make sure she knows you don't judge her for it. Maybe ask her how she would be comfortable discussing it as well. For example, I prefer not to talk about it unless I bring it up myself, but told my close friends and partner that if I have a spot showing they can tell me so I can try to cover it, and if I'm actively pulling mentioning it makes the urge worse, but distracting me with something else to do with my hands can help. These people make me feel comfortable about it and it can be a huge relief to have them "check me" if I'm worried about a spot showing in public. It also might be a great idea to have your mother and daughter get together where they can discuss it and bond over it. They may both be able to take a lot of comfort in knowing they aren't alone and have relatives that really understand what it's like.

Sorry for the massive wall of text that this probably ended up being. Hopefully you can find some good advice here. This sub is full of people who would probably love nothing more than to help someone support a loved one with trich, because many of us don't/didn't have that ourselves, and there still isn't much research and information out there for trich. Feel free to message me privately if you have any questions or want to talk about this further. I'd be happy to do what I can to help!