Something to think about might be diversifying your 401(k) with bonds (vanguard total bond would be good), international equities, and mid/small cap (the 'extended market' vanguard fund). My allocation (similar age/life situation) is something like 10% bonds, 30% intl, 15% small/mid cap, 45% large cap, just as an example. Diversifying (in general) tends to improve returns while reducing volatility.
You probably do have too much in cash. As MDM's link notes, timing the market is usually not a great idea. People have been saying the market is overvalued and predicting a crash for several years now, and anyone who listened in 2014 and cashed out is kicking themselves pretty hard right now. Definitely invest the Roth money in something, and consider opening up a taxable account for (some) of your cash savings. The likelihood you'll need 2.5 years of e-fund is hella low- even if you move out and expenses double, you've still got a more-than-healthy cushion.
Speaking of expenses, do you have a detailed budget breakdown? Living with folks, spending 11k a year seems a little high. Again, I'm in a fairly similar life situation to you (minus the living at home), and my non-housing spend is something like 6.5k. So there may be places you could make some cuts to a. save money now, and b. make the transition easier when you have to start paying rent.
Overall, seems like you're doing quite well, though.