My mom was much as you describe your mom. Without writing a book, I found that the best way I could handle her 'neediness' while juggling a job and 3 small children was to do the best I could, tell her it was the best I could do, sometimes let that phone ring when I couldn't bear what I knew I'd be hearing, and then I'd call her when I was strong enough to have a "decent" conversation.
My mother knew I loved her and would do anything to make her life as good as it could be. She had many, many people fooled on some things and they as much as let me know what a crappy daughter I was. But as I said to my husband after mom died, I saw none of them lying on a bed in the hospital floor, making sure my mom was okay after major surgery like I did, pregnant and all. None of them was there fighting with a floor nurse to get her off morphine while she wildly hallucinated. None of them were her daughter ..... I was, and I did the best I could.
You have a lot on your plate, she knows it. Keep loving her, cut off contact at times if you have to for your sanity and you can have a better relationship because you're not bone weary with her demands....................just my humble opinion. But I have been there, done that, and trust me, she knows you love her, that's why she's manipulating as well as she is, lol.
Hugs,
Bets