Feeling like a shitty mom

Alright y’all I need some advice. I have a 2 year old and am currently pregnant. My 2 year old won’t listen whatsoever. All she does is scream, throw tantrums, headbutts and slaps and pinches. I don’t know what to do and I’ve started spanking her and I never wanted to be that parent. I don’t like spanking because it doesn’t do anything for her and she just hits back after we tell her not to hit. Please help this momma out and help me figure out what to do instead of spanking her poor little bottom 😭