Until she is around 6 months old I would buy something that can last her till then. Then I would measure her up and call Equafleece for advice. That's what we did and we bought 2of them and they still fit her. Considering that they are not cheap, it is better to wait.
I agree with Neil. No discussions about whether dogs should wear clothes or not. When I see Peanut shaking every single time in the park in winter, the decision is taken for me.
I don't know if you know but Spaniels do not regulate their body temperature effectively, it is an issue with the breed. They get very cold and very hot and they have problems adjusting their bodies.
I am glad I kept the little one I bought her when she was tiny. That lasted until she was around 4 / 5 months. Coconut will use that and then move into one of the equafleeces (as if it was all planned!!)
