I admire your struggle to cope with your mother and appreciate the fact that you want to do something about it. But my response isn’t going to be about improving your communication, it is going to be about improving your individuation: It is time for you to plan to move out.
Everything you have described about your mother is the fact that she is restrictive. She seems to limit you in many ways. While it is just a guess, my experience with other people in similar positions to yours is that the suicidal ideation is often the result of an unresolved anger. Don’t let these thoughts continue to happen without getting some help. There are three things I think need to happen.
Secondly, I would encourage you to become involved in group therapy. This can be through NAMI, the National Alliance on Mental Illness. You may also find groups offered through your local hospital. The link will help you find meetings in your area. These options will either be offered for free through NAMI, or on a sliding scale at the hospital.
Finally I would develop a plan for moving out and becoming independent from your mother. The plan could be for a year, but it should allow you to be more on your own. As part of this plan my hope would be for you to return to college so you can support your independence.