At 23, the thought of dating anyone under 21 is not ideal to me.
Haven't touched WoW in almost 3 years...I'm happy to say I'm finally off it. I did just pick up GW2 though...
i5-3570k quadcore @ 3.4ghz - 24gb DDR3 - 128gb SSD Boot Drive / 2x 1TB SSD (raid0) - Radeon 4gb 290x, 3 24-inch HD displays, dual bonded 1GB network links to my home cisco network lab
You can't put a number on relationships. There is no math. There is no formula.
Whether she is 17 or 18, if you find her interesting enough and attractive, then there's nothing holding you back from pursuing the chance at a relationship with her; nothing, but the taboos of our society.