I'm a hat person too, both summer and winter, for practical purposes (sun protection) and style.
Not collecting anymore but my most recent acquisitions over the last few years are from Maison Michel (mostly Virginie style), Filu Hats and Nick Fouquet.
My head is smaller than average (54cm) which is a pain! I used to get hats made by a local milliner but she retired so it's back to off the rack. Often I resort to using my longish hair tucked up under the hat to keep a too big hat on my head.
My seasons are opposite to most here, currently wearing my everyday Maison Michel Virginie in navy felt with black trim. Pictures to follow.
Are you into vintage items? There are lots of beautiful vintage hats that run smalll.