I would be curious to see how your numbers would look if you got a 3/2 and househacked (roommates) or continued to live with your parents while you turned that place into a MTR. 

Note: if roommates change during the tenancy, a lease addendum is signed and the security deposit is called out so that there will be no confusion in the future, 'The Landlord and the Tenant's agree that . . . '  This lease addendum may also guide your bank record when the funds are withdrawn later.

Perhaps, you have a recommendation on a local (Houston) real estate agent that can help me locate tenants/roommate? 

Are you looking to get an investment property at 20% down or a primary residence you can house hack (rent the rooms in the house you are living in), or a primary residence (better for people who are married/have kids/don't want roommates) where you live in it for 12 months then rent it when you buy your next property to repeat the process.

It also states that any security deposit refunds owed will be made payable to all parties on the lease agreement.One tenant has stopped contacting the roommates and us, and we are not sure they are planning to return.

I know this works for STRs, but I feel like it may be awkward for an MTR considering the nurses will essentially live together and be roommates for several months.

Typically it is still hard to have it covered without a roommate if its not in a C class area, but it is possible @Chris Schoonhoven

And if you're up to it and you're buying units that are 2 bedroom - take a roommate. 

This structure seems to work best for house hackers looking for roommates in their friend group to help cover the mortgage.

The other option is ask her if she wants to find a roommate and they can split the rent.