I don't grow that one but there are multiple lavenders without a mauve or reddish tint.

I have some pics of mine, the link is below. From your description I'd say you won't like Twilight and you will like Prince Charles and Juuli.

Here is a link that might be useful: My Clematis Pages

Lovely photos of your clematis, LeeAnne.

ilseschuhe, have you looked at Will Godwin? It's pretty close to blue to my eyes.
My second year plant has several buds. I can hardly wait for them to open. Last year the plant had one bloom when I got it.

I have grown this one for years . It is an easy grower
and it is a clear light blue--no hint of purple at all--with a yellow center. I have mine planted in a large pot on the deck with a round iron trellis thing ( that fits into the pot). It is a beautiful cultivar of an unusual
seldom seen color. My VERY favorite Clematis of all time, though ,is 'Ivan Olsson' -It is creamy white edged in blue --gorgeous! Both of these are available from Brushwood Nursery in Wa.