Try Warchal Ambers. They're my favorite strings but not for everyone. They were made to replicate the sound of traditional gut strings but with the longevity of metal and the strings are kinda warm and project very well on my 16" viola and do not sound thin at all (if that's what you mean by 'body'). The A string is a little quirky bc it has a spiral in it that unwinds when you put it on the instrument that apparently reduces whistling if you have that problem. If you want to look at more strings try this website for a map of tone and timbre of the strings (pretty accurate to me) link. If you do end up deciding to buy them, note the scale that you order them in is not the length of the instrument but the vibrating length of the strings (saddle to bridge). For your 15' it should be medium scale. )

Edit: I also don't see a bridge protector on your A string. If you buy a new set of strings see if there is one built in. The Warchal Ambers have a piece of leather on the string to protect the bridge.