Saddle Fit question for Novice Open Show Rider

I grew up riding western and have limited knowledge of CC or AP saddles. I want to purchase a saddle I can use for open shows. I am unsure of the seat size that I need. I tried a 16" L & R CC saddle with a medium tree and felt it was pretty tiny, thought it fit my horse. I am 5’2" and 130 lbs. I am riding a 16+ hand narrow horse that has very high withers. I am definitely in the market for a used saddle. It doesn’t need to be perfect, but I want a solid saddle that fits both me and my horse well. Any recommendations? Thanks for your help!

I am your heigth and weight and both my dressage and close contact saddles are 17 inch seats. You might try to find a knowledgable saddle fitter or person at your local tack store who can help you with both saddle fit for you and for your horse.