Think about the real time horizon of your investments, probably like 10/20/50 years. I know it seems like a big worry now, but on that time scale it won't matter too much.
I wouldn't call it a big worry, I would call it a small detail -- but one which I have the opportunity to optimize, so why not optimize it?
Get on investing more. Maxing out your 401k and IRA is good, doing that and contributing to taxable is even better. The amount you invest will make a later difference than how you allocate (probably)
I've been playing catch-up: I got a higher-paying job halfway through last year, maxed my 2015 HSA between July and October, maxed my 2015 401(k) between October and December (contributing 100% of my paycheck for a while there), and maxed both 2015 IRAs between January and April. That's in addition to the $2870.83/month to max the 2016 401(k), HSA and IRAs with equal payments throughout the year. My wife had been underemployed but got two different part-time jobs/contracting clients in her field this year, so she became eligible for two different 401(k)s in the last few months. Therefore, now I'm trying to shovel as much of her income as is allowed (75% max contribution for the W-2 job and 100% of the 1099 income) into that, too. And we're paying off student loans.
(That's something like $60k worth of investing projected for calendar year 2016, not including paying down the loan principal, but it all fits in tax-advantaged accounts because some of it is for tax year 2015.)
Once all that's done including paying off the student loans, which will probably be in about 2018 or 2019,
then I'll worry about a taxable account. At that point I might decide to invest in real estate instead, though.
Out of all those accounts, the only ones with good international fund choices are the IRAs and my wife's 401(k)s (which are/will be with Fidelity). I disregarded the latter in my posts so far because she's only got $2877 in one so far (we have ~$4k in our checking account to contribute to the solo 401k, but haven't finished submitting the paperwork to open it yet).