Just make sur you dont do things that really irritate her or get on her nerves!
For example my husband really annoys me when he brings empty cups into the kitchen and puts them above the dishwasher when it just takes a couple more seconds to put them in the dishwasher!
If shes goes off on one. Just take a deep breath before you anser. No doubt if she may also get stressed due to lack of sleep. I should probably ask if she is a mum yet or not?
What are you normally doing when her mood changes. Maybe you could try and avoid these moments.
I think you are doing a good job by the sounds of it. If you are trying to make things easy for her just to please her, make sure you arent holding things in and getting stressed yourself. If it helps write her a letter of how you feel etc and give it to her when shes in a good mood. When my husband got stressed before we were married or we had some sort of discussion and I would whinge at him for not doing enough studying. Hes way round it was to write me a letter....
I dont know if any of that has helped.
If anything is bothering you just ask ,