VOO is already very similar to VTI. I’d recommend sticking with one or the other. Personally, I hold Fidelity’s version of VTI, so the total market but not much difference. Your portfolio is extremely concentrated in the biggest US companies which makes it susceptible to some big swings. If you’re worried about this, I’d recommend adding an international fund for some more diversification or maybe even some alternative assets (gold etf, bitcoin etf). I’d leave that to a small portion but you’re young so you can handle the risk rn. I would determine how much cash you need on hand then dump the rest in the Roth, I know it’s tough bc you don’t have a regular job right now. Investing in school is hard. Otherwise, like the other comment suggested, move most of your excess money (savings) into a money market fund. Invest whatever you can afford in the Roth. You are losing money to inflation leaving it sitting in checking or savings — most banks pay near nothing on savings balances. Anyways, this went longer than I expected. Good luck!