I don't have a clue what brand shoes Lois might wear, but I do agree her clothing got more up-scale in Season 3 than it had been in S1 and S2.
As for this:
It was quite common to find dress shoes and heels in women's sizes 11, 12, and even 13
You are absolutely right about that. I wear a 10 or 11, depending on the style, and it often seems like all that is available are heels. I'm tall enough as it is, I don't need to be walking around in 3 inch heels, but that seems to by what the shoe manufacturers want me to wear. <shakes head>