I can't be the mum she needs

I got diagnosed about a month ago. Part of the reason I went for the assessment was because I see my little girl (age 5) struggling like i did. She reminds me so much of myself. 

I desperately want to be the mum that I needed as a child but I genuinely dont think I can.

I get frustrated at her random noises.

I get annoyed when she complains about feeling the seams in her socks and then refuses to wear them.

I get annoyed when she will only eat beige foods.

Im exhausted from constantly getting up in the night with her because shes anxious. I try so, so hard to be patient and give her the reassurance that she needs but I need sleep too. 

I am trying so hard and I usually start the days off ok. But by 5pm when ive spent all day being overwhelmed, masking, being touched by my 3 year old etc, I just can't keep calm. And that's usually when she needs me the most when shes home from school and needs me. 

I dont know what to do. I know im a terrible mum.