Could you just say that to your mother? Just tell her what you said here. In a letter or a text just tell her you would like a better relationship with her and are looking to see if she is open to the idea. You can explain it is important to you. Be direct and ask her what you would like. Everyone communicates differently and perhaps she did not understand this as a method to improve the relationship. If she says no, perhaps she will give a reason. If not you can say okay and ask her to let you know if she ever changes her mind. Unfortunately we cannot always have the relationships we want but it is best to be direct about your needs and also boundaries. But also know that just because you want or need something doesn’t mean you will get it if you ask. I often find we do not directly ask the questions we really don’t want answered. It is possible she will say no and give no reason and that will be sad but at least you did your best to communicate with her. But perhaps it will open a door. In my own life I often didn’t directly ask for what I needed and tried to pad the questions do as not to be rude or hurtful but sometimes people can’t see what you are asking that way. When I asked directly I was often surprised by the answers in a good way. Good luck.