Youngster IRA Allocations

25, been working a few years

Contribute 10% to Roth 401k - split among a few funds: large growth, mid cap growth, large blend & S&P 500 index

I have a normal brokerage account with a little bit of money. I dabble with a few individual equities and have made a little bit. Planning on using this as part of a down payment in a couple of years.

Also have a Roth IRA with max contributions the past few years. Currently I have these approximate holdings:
37% VTSMX (total stock market index fund)
22% V (not at the advice of BigFella -- my own thoughts as well as a suggestion from a very successful person close to me)
20% BFOCX (Berkshire Focus - tech growth fund)
22% Misc funds and equities that I've owned since I opened the account 7 years ago.

I am about to add another 30% to my IRA, but I would like some basic advice of where to go with it. I originally planned on increasing the VTSMX holding, but I feel like I have a significant majority of my 401k and IRA in large cap and index funds, and I'm not sure I want to put another big chunk of money towards an index fund at an all time high right now. I know the basic thought process on index funds is that they will outperform individual equities in the long run, but I just feel weird buying an index fund right now.

Any suggestions? I'm open to individual equities, but I would probably prefer funds. Or if I should just suck it up and buy VTSMX again right now, just tell me I'm overthinking this.

tl;dr - scared to buy an index fund at an all-time high. where should a 25yr old put his retirement money?