New BP Owner seeking advice

[Kata]

Hi everyone, after a lot of consideration my husband and I decided to add a new member to our family. Khaleesi our BP joined us 2 weeks ago. We bought Khal from petco and since we purchased her I have heard that petco underfeeds their snakes. When we got her they were not able to tell us when she was hatched and they said that she was on pinkies and had tried one hopper. We bought hoppers for her but I do not think it is enough so I went and bought 3 adult mice today (we are feeding frozen). So I was hoping that maybe by looking at some pictures of her we could get some advice if we are feeding her the right size.
Also she just shed for us and it was not a good shed, but we have been fighting with the humidity levels in her tank, it is very dry where we live and getting her tank past 40% humidity has been a battle. We did go today and buy her a monsoon RS400 to try and help and now the humidity seems to be ranging 50 - 60%.
The heating in her tank is averaging 75 degrees on the cool end and 85 degrees on the warm end.
I am really in love with this snake, she is just amazing so I want to make sure that we are doing everything in our power to take care of her correctly. Any advice would be appreciated.
This is our girl:

[KMG]

There are two main methods of picking the feeder size for your snake. The first is to eyeball it and feed prey that is about the same size in width as the thickest part of your snake. The second is to track the weight of your snake and feed prey that is 10-15% of the snakes weight in grams.

I good trick for adding good humidity for your snake is to place moss inside the hides. During a shed I keep the moss damp until its complete. During non shed times I make it damp and allow it to dry out before making it damp again. This creates higher humidity in the hides which benefits your snake greatly since the hide is where it spends most of its time. This means that your tank humidity doesn't have to be as high because the snake is getting what it needs in the hides.

[Kata]

Thank you for the advice, I will try moss when she is ready to shed again.