Ok, I can see how it has sexist elements, due to even the strong female characters being portrayed in traditional roles. I don't think you're wrong there.
I do wonder why it's a bad thing to portray feminine qualities in a positive manner, though. As in the mother's sacrifice... yeah, it's a little bit cliche. I still don't get why it's bad. Molly Weasley... yeah, she has a lot of kids and is trapped mainly in a role as a mother figure. I don't understand why this is bad. I think it's realistic. I personally think it's great that it's both realistic and positive. She's the iron-fisted, overwhelmed mother with a henpecked husband... and it's portrayed as not a bad thing. It's just how their lives turned out and what works for them, as it is with so many people in real life. I get what you're saying about McGonagall, but keep in mind that the setting is supposed to be a parallel to the real world. If we assume that the wizarding world has roughly the same history of patriarchy behind it as the muggle world, then McGonagall is a pretty spot on portrayal of a woman at that age in that position. These characters are all believable and positive to me. That wasn't an exhaustive list of strong female characters, either. I get that you're disappointed with Ginny not turning out uber-powerful, but she was portrayed as having lots of potential. It just didn't come out in this story. There was also Tonks, who I thought was really cool. These are just the ones that had the most prominent roles in the story, and that I can think of off the top of my head. My impression of the setting as a whole is that women were equal to men in practice, but that their society's gender politics were in roughly the same place as ours.
And I agree that the list of developed female characters is shorter than the list of males, but I blame this on the book having a male lead and being guided mainly by his perspective. There is absolutely no reason the book couldn't have had a female lead, other than market potential... and I'd be surprised if this wasn't Rowling's prime motivation in designing her main character. This is something I can 100% agree on as being a bad thing. I'd like to see more popular fiction told from a female perspective without being restricted to something like The Princess Diaries.