First lager? Hence your premature expectations... it will not taste good, or remotely like it eventually will, at 11 days.
It’s not too late at all for a d-rest. Mind you, a d-rest is usually just precautionary, not necessarily mandatory. If the yeast were treated kindly, they will not have felt abused and won’t have produced diacetyl in the first place. So don’t sweat it. Raise the temp to 65 and let sit for 2-3 days. That will also help clear the sulfur. But so will sitting at 50°. It’s just a matter of longer time at the cooler temps.
I keg my lager after two weeks of primary. I find that, nearly without fail, it takes another 2-3 weeks in the cold (lagering!) until it suddenly gets that flavor, texture, and carbonation that make me say YEAH, that’s bloody good. And then it only gets better for at least a couple more months.
Patience.