It is always better to use a equine brand jacket because they correspond to all the movements and do not restrict them. I recommend the website: https://www.equestriancollections.com/ladies-riding-apparel/ladies-riding-coats/riding-jackets
They have a wide variety of choices, I hope you will be able to find something. If these are too expensive, Horze is a good other choice:http://www.horze.com/winter-jackets
I hope I was a little helpful and that you will find what you are looking for!