As a very anxious mother, perhaps just text of make a phone call to her once a week so she knows you are OK?

If seeing her is triggering or hurtful--it is OK to limit how much you see her. It is more important that you take care of yourself.

It sounds like you love her. We can love people but recognize that we are unable to help. My POV is our relationships with our parents are complicated by the emotional connections made with them when we were too young to even understand it all. That makes it so that the subconscious emotions between us get in the way of the relationship some of the time. Or perhaps there are unresolved issues that cannot easily be resolved. Once you are 18, you have a right to make your life be what you want it to be.

Be respectful when you are with her, but whenever she is triggering, politely leave, hang up the phone, etc. Check in but only check in as much as you can handle. It could be once a month (I cannot determine that as it is a very individual thing). Do not feel guilty for taking care of yourself. Taking the time to take care of yourself is the best gift you can give to your mother. It can be hard to handle an anxious person if you are also unwell. I do not know if you are unwell, only saying that, as an anxious person, I know that I can be challenging to deal with sometimes. Hugs.