I have only fed her once since I just got her last week (received her on 02/08, successful feeding on 02/09) ... the breeder I received her from said she was eating "small adult mice weekly", but small mice looked too small to me, so I got medium

I would say, even the medium mouse didn't make an very obvious lump after she ate, but she happily took it and seemed satisfied by it

I almost get the feeling she could already be hungry again already though, but not sure, I could be mis-reading cues ... I would say the medium mouse was as big, maybe even SLIGHTLY smaller than her thickest width

I was planning to feed once a week, every 7 days, but maybe I should do 5 days?

At that weight what do you think is the right size rodent? Maybe try a "large adult" mouse instead, as long as it's not too much bigger than her? I've seen conflicting advice that the prey should be slightly bigger, or exact size of the largest width... I'm not 100% sure on what I should be feeding and don't want to overextend her