You say you are heavy on "Vanguard Index funds". I'm not sure what that means. Vanguard is just the company that handles the administration of the grouping of stocks you own. They are the people who package those stocks into bundles--aka mutual funds--and deliver them to you. There is no reason to go outside Vanguard, just because every thing you own is currently Vanguard, unless they don't bundle the product you want to own. It's a bit like saying your groceries are Publix heavy so you need to shop somewhere else when you go to purchase flour and ground beef. (Maybe I misunderstood your question and that comment?)
I would continue to invest in Vanguard funds as it's easier to have everything with one broker, and they offer everything a typical investor needs. Your portfolio seems light on bonds (you don't give $ amounts, but probably less than 7% of your total so you might consider increasing that. This makes your portfolio more stable. Less risk, but of course the corresponding decrease in possible reward (but also in possible loss).
So really, the question you should be asking is what your asset allocation should be, and that depends on your goals, your risk tolerance, your timeline, your job security, and more. I'd start with a google search of "common portfolio allocations" and tweak from there as needed.