I don’t think you’ve stopped loving your daughter. I think you’ve stopped loving the struggle of being a single mom with issues of your own. Managing yourself is hard enough. Parenting on top of that must be exhausting indeed. Perhaps some of these ideas will help you address that.
I’m concerned that you say your whole life is devoted to her. Of course, parenting is a big job. But she shouldn’t be the absolute center of all you do. You didn’t mention if you have a job, your own interests, and a circle of friends. You didn’t mention if you are in treatment for your mental health issues. If not, those are the problems, not your daughter.
School will be starting soon. Research after school programs to keep her busy and happy with her peer group. Try to find an activity she would enjoy for a block of time on weekends so you have a break then as well. Organizing her time will give you time to work on you. It will also make your time together less stressed and more enjoyable.
If you aren’t working, find a volunteering opportunity that will help you find friends and build your own self-esteem. If you aren’t in a DBT (Dialectical Behavior Therapy) group, research where you can get that kind of support. Take advantage of whatever supports are available to work on your own issues. See if you can find a support group for single moms as well. Take a look at the forums and support groups here at PsychCentral to see if one of them would give you additional online help.
Yes, organizing all this will take some effort. But once you put supports in place, they will be there for you for a long time. You can then be the mother you want to be and that your daughter deserves.
I wish you well.