Best support Sona build?

So my recent auto fill game I went with Sona (and had a blast btw, wish more people would suck it up and play their AF games) and with good kill participation I was able to get fully geared up rather quickly. I went the normal support build path and ended up swapping around some items for and as I was being melee focused and we needed more AOE damage for clear but only at the last 5 or so minutes.

My question came when our jungler asked why I didn't stack AP and then asked if I would and at the time I thought hell no, he may not realize it but the only reason he only had 3 deaths and we won the majority of the team fights was because of the shields/healing, but now it's got me thinking as I don't play support that often anymore. Would a damage build been better in a game we were ahead and destined to win or was I right in my decision to stick with proper support items?