It's always hard for me to dress when the weather is being indecisive. All I want to do come spring is break out my light weather jackets and cute sweaters, and one day it will be possible, then the next it'll be so cold and I'll have forgotten that I need to wear a heavier coat.
The perfect thing for this time period is a bit of what I like to call transitional dressing. Coats that are just heavy enough should it be breezy and chilly out, but cool enough that if the sun came out and the temperature warmed up you'd still be ok. Maybe undo a button or two, but it's not like you're wearing your vintage wool and are sweating under your layers!
I started breezing through my first go-to's for this search (etsy and ebay) and came up with a couple cute selections. A nice variety for your size and taste.
There are also tons and tons of vintage clothing dealers online where you can find similar style clothes, perfect to take you from winter into spring! Remember to always check and ask for measurements, as vintage clothes are not sized the same as today. I have a few items that were claimed to be larges, and are really about a small in today's standards. Happy hunting!