Failing as a mom?

I have a little one who is 17 months old, and I really feel like I’m failing her as a mom. During the day, it’s just me and her all day. I’m currently in school to be an RN in hope of giving her the best life I possibly can. Right now most of my school is online because of Covid, so that means I have her and online lectures that I have to be on camera for at the same time. I don’t get to have a sitter except for days I have to go to campus. Well, she is use to being the absolute center of my attention all day, and sleeping on whatever schedule she wants (has NEVER been a good sleeper, so we take what sleep we can get). Now that she has to share me with school, she is really acting out. She use to listen to me when I’d tell her no, or to come here. Now she just pretends I’m not talking to her and does whatever she wants. She’s into taking off all her clothes the second I turn my back and peeing or pooping everywhere. Anytime I have something to do where my attention can’t be on her, I suddenly become her human jungle gym. She just really fussy with me, so much so that I’d say she’s angry. She doesn’t act like this when her dad gets home. She’ll listen to him, play with him, etc. If he rocks her to sleep at night, she’ll fall asleep in about 3 minutes every time. If I try to rock her to sleep, she’ll fight for hours just to stay awake. She’s started hitting and scratching me when she gets upset. I don’t hit or swat her. The most she gets is a couple minutes time out in her play pen. Again, a behavior she doesn’t do with her dad.

Having a sitter is a recent thing for us as well. When the sitter sends us pics of her throughout the day, she looks so happy and like she’s having so much fun. And the times I’ve gone with her dad to pick her up she’ll run to him and just look at me, or pretend I’m not there. I’m sure a toddler isn’t really capable of hating someone, but I feel like her least favorite person. When I see how she interacts with other people I feel like maybe she’d be better off with another family, happier at the least. Her dad is barely around due to his work schedule, so she’s with me and I’m guessing unhappy 99% of the time. I try so hard to do the best for her and make her as happy as I can. I just feel like I’m failing as her mom. I’ve wanted so badly to be a mom, even since I was a kid. We went through years of infertility and recurring miscarriages before we were blessed with her. And now I’m just feeling like I wasn’t meant to be a mom at all. I feel like I’m so bad at it. I just want her to be happy, and I know she can’t be 100% of the time, but I also feel like she’s just miserable with me.

Has anyone else felt like this? What was something that helped you in your situation?