First thing you must do is distinguish between a health insurance *company *and a health insurance policy.
A health insurance company writes many individual policies that include or exclude various types of coverage. For example, a “major medical” policy would only include things like hospitalization and such, not regular doctor’s visits, etc. Some policies cover mental health services, some don’t. Some cover infertility treatments, some don’t. Some cover prescription drugs, some don’t.
When purchasing individual health care coverage from an insurance company you can select from among policies and coverage. When an employer is building a plan for its employees, it does the same.
Now, abortion might be in Policy A and not in Policy B of the same insurance company.
Many states require abortion coverage to be in the plans employers provide. Same with contraception.
So, I don’t know of any insurance company that does not include abortion in one or more of its policies. If you are buying insurance on your own, you can get a policy that covers what you need-- abortion may not be in that policy. But, it might be in someone else’s.
That said, there is no need to get off your mother’s insurance. You are not having an abortion, therefore you are not doing anything wrong by being on this insurance plan.