@Nathaniel Prince I would start with what @Carl Millsap posted.
What's your goal?
Do you want to create cash flow to reach what I call the "TFP"? That the point in time where you no longer have to exchange your time for money because your passive income covers or exceeds all your expenses? If that's the case, you should follow a strategy that gets you to your TFP sooner rather than later. The term I try to get people to use for that approach is "Performance"
If you rather aim for appreciation of the properties in your portfolio, your purchases and sales would be different.
It might sound pedantic, but being clear about terminology has helped me make sure I can determine what my next steps should be (or if people ask for my help, to make sure we speak about the same things).
With that in mind, I don't understand why you say that you did not get the ROI you were expecting? I don't know about your property but just as an example:
If you bought for $300K with $100K down payment (33%) and you made $100K appreciation in 3 years, you got 100% return on your investment(ROI) not even counting tax benefits and assuming $0 cash flow. If you put less than 33% down or had at least a little cash flow, you have even more than 100% ROI.
I would say that's awesome.
Naturally, you never know if past experiences will be the same in the future.
If I had/owned that property I would get a HELOC or all-in-one loan. You can probably only get 80% of the equity but if you had $100k appreciation and probably your downpayment + some principal, you might have closer to $125K equity, which should give you about $100K in your HELOC or AIO-loan.
With that money, you can buy 5 well-performing properties @ $100K each from a turnkey provider and use the positive cash flow to pay back the HELOC/AIO-loan.
If circumstances ever require, you can use the cash-flow money for expenses and you still have your original appreciating asset + 5 more assets. If you are lucky, they don't just perform well, they might also appreciate on their own, even though it will probably be at a lesser rate than your core-property.
In the current environment, it is a very smart strategy using low-interest rates as leverage. I am retired Air Force myself and building a passive income stream for the time after your service ended is a great approach I wish I would have known about when I was still on active duty.
Last point: I suggest taking advantage of your financing benefit as a military member. While I would love to see you follow the suggestions above, I would also look for a triplex or 4-plex and buy it for yourself using your zero-down VA loan.
If you stay where you are for 2 years or more and then PCS, you can get a new VA loan in the new assignment location and if the military requires you to move sooner you automatically get your eligibility back in the new location. I believe it's part of the military clause. Same as when your tenant is military or joins the military, you can't mandate them to stay.
I called it my "Hensel & Gretel- Strategy" when I was still on active duty. I left a house I bought with zero-down VA loans in each assignment base, rented it out after I left, and had a small portfolio that I consolidated into a real cash-flow portfolio when I retired. The locations were not always the best performing, but with none of my own money to lose and all the time in the world, ultimately the houses either appreciated or the rent was good and sometimes even both.
Sorry, I typed too much already. If you like to talk about it, let me know in PM and we can set up a call.