That's awesome! I hope to be in that same situation. I'm pretty far off from retirement (in my late 20s), but I'm debt-free and nurturing a small nest egg.
I think that nurses can definitely make a decent wage, depending on your circumstances and lifestyle. My first year as a nurse, I lived below my means in a small non-luxury apartment, and made enough money to put 20% of my salary towards my 401k while taking home enough savings for a down payment on a house. If I spent a ton of money on luxury vacations, or if I were a single parent of multiple kids, I might have a harder time putting money towards savings.
If you're mobile, you can also maximize your earnings by living in a city with high nursing salaries relative to cost of living (northern California, Phoenix, and metropolitan Texas come to mind). However, you should probably stay away from NorCal until you have nursing experience, since the high salaries make new grad nursing jobs almost impossible to come by.
Keep doing what you're doing: make a plan, stick to a budget, and live within your means. Like PPs have said, even if I have the ability to retire at 50, I love my work and I'll probably a crusty old bat hobbling around the NICU at the ripe old age of 70 (probably part time, though