As population grows, housing demand increases, driving rents higher.Rapid and Sustained Appreciation: Not all cities with growing populations appreciate rapidly.

I have my primary property which is a single-family house that I house hack.

I saw that the population grew by 5% from 2020 and I haven't seen much development as far as new housing goes so what could be causing this uptick in time on market? 

Quote from @Duane Williams: We’re a family-owned fix-and-flip company operating in San Antonio, TX, and Northern Virginia, managing everything in-house—from wholesale acquisitions to rehab & construction (with our own project managers and crews) to listing & selling through our licensed brokerage. 

Assume break even cash flow while rented which includes a generous $600/mo repair fund. 

I house hacked then rented it out after a year.

If you're willing and able, I do recommend the "house hacking" strategy which is just a fancy name for buying a rental property and living in one of the units, because you'll get very favorable financing - an owner-occupied fixed-rate 30-year mortgage.I'd also say, analyze that property as if you won't live there and it's a pure rental, and make sure the property is still cash flow positive if there's a tenant in your unit because then you'll know if it's actually a good investment.And when you analyze it, include payment of a property manager in your #s because if you don't, and doing so would make it go cash flow negative, then you've just bought yourself a job because you literally can't step away from managing it without losing money.

If you want less leverage simply put down the funds you would use to pay down the 6.4% rate on the new property so you are at say 60% loan to value on the new house.

Lowering your standards invites expensive evictions and repairs. 

Your realtor will be able to give you a much more detailed market specific answer but with house hacking and a VA loan it should be possible to get 0 out of pocket.