Moms of more than 1 kid

Is anyone really struggling parenting multiple children??

I have a 6 week old and a 4 year old. I’m really having a hard time with my 4 year old and feel like I’m constantly yelling at her because she’s been testing me so much. She’s not listening; she’s making me be the “mean mom” and I hate it.

I also feel bad because I haven’t given her/am unable to give her more attention. My newborn is awake a majority of the day now and still wakes every 2 hours at night, so I’m exhausted. My husband works every day and I feel like my toddler deserves more. But I don’t have more to give 😔

I don’t know if this is natural or if I can do something better, but I don’t want my 4 year old to end up hating me because I’m saying “no” and sending her to her room so much more since my baby was born. She’s always been stubborn, but it’s amplified 10x worse now. She’s throwing so many tantrums and is super whiny over everything.

Any advice or anybody feeling the same?