Yah the average wait time takes tanks/healers into account so your 45 min wait gets balanced with the tank's instaqueue making the average 23 minutes. Don't fret by the way if you don't see anyone else being paired with you. It seems the Duty Finder doesn't like to put together parties without a tank first. Pretty much the only time I've seen more than myself in that window as a DPS that weren't tanks was when a tank would withdraw from queue. Usually once a tank enters queue and you're at the top of the DPS pile the party instantly forms up.