Don't scourge yourself... you must live with your own problems, your mother's, your illness, plus all your self-criticism? It must be indeed exhausting. I know it's easy for me to say and much harder to implement, but you must start by getting a blank sheet of paper describing where you are now and what you'd like to accomplish. Once it's much clearer in your mind, use your T as a resource and make the most of it, be concise, don't lose so much time doubting or stepping into other people's shoes thinking what they might think... everybody is a grown-up here, if they have a problem with you they'll tell you... just make sure your mother understands (your therapist might tell her) that you're struggling, but making the upmost effort to improve (and you do seem to care about improving and doing the right thing in your post).

Living with other people is difficult. Take responsibility for your part of the bargain but remember that maybe you're not 100% to blame: do you think your mother listens to you? Is she aware of your inner struggle? Is she supportive or rather absolute and smothering? Mine was/is some sort of dysfunctional family as well (so common these days), but if you believe that your father might be some sort of good/alternative influence you might try interacting with him to see how things go... Only if you feel right about it, but having supportive family members and some friends is a life-saver for us, I tell you, I wish I had more of those.

Lastly, pls, don't be your worst enemy and stop saying you're a failure... you're still young (take advantage of it) and a work in progress, just don't desist or surrender before better times come. Have faith and persevere.

(((Hugs))).