I agree, contributing to a Roth IRA was a smart move and is probably your best investment option right now. You're young right now and will likely move to a higher tax bracket later on so the more money you can stash in your Roth at lower tax rates the better.
VTSAX should be the cornerstone of your portfolio. You may also want to consider adding an international equity index fund (such as VGTSX) and maybe a REIT fund to diversify further. At your age, you don't really need to concern yourself too much with bonds but down the road you could allocate a small portion of your portfolio, say 10-20%, to a bond fund. Bonds can help temper some of the volatility of stocks and when the market inevitably takes a dive, you can sell your bonds to pick up more stocks at a discount.
Apart from your retirement and emergency fund savings, look into a taxable investment account as well. You didn't say when you planned to retire but keep in mind you can't take money out of your tax advantaged account until age 59.5 (except for Roth contributions). So if you want to retire earlier, you'll either need another income stream like a rental property or sizable savings in your taxable accounts.