Tomorrow I will be in continuing education for eight hours of my life that I can't get back, to maintain my license.

I have attended a few local REIA meetings and will definitely continue. :)

I would continue to research them and vette them. 

Looking in G'ville and Jax.I would think that all Realtors are good. they have a licencethey have been trained in the ways of representing others for a feethey have to go to continuing education coursesthey are regulated by the statemost are bonded and have error and omission insurancethey are members of the local MLSmembers of Boards of Realtorsthey are motivated to earn income from listing and selling real estatemost are not real estate investorsmost are sincere and anxious and ready to earn a commissionLicencee are trained to represent others for a commission and to protect the public from fraud. 

That's a span of time you can't even fathom at your age.2)  BUILD a SOLID FINANCIAL FOUNDATIONGet your credit score to >700 (there's a ton of info on how to build your credit anywhere on BP or Google)Obtain or continue earning W-2 income (this becomes important when you want to obtain a mortgage down the line)Pay down any bad (consumer) debt and don't pile on any additional bad debt.Start saving.

I used Buildium software, which has a listing feature, and that lists the units on Zillow, Apartment List, and Rental Path, and then from there other services pick up the ads and repost them.

I also like the north Fort Worth area, with a lot of new construction I feel like the area will continue to increase in value. 

You are correct, if your intention is not to continue with your side self-employment business activity then Solo 401k would not be the best choice for you as you would have to terminate the plan if the plan sponsor ceases to exist.While self-directed IRA LLC does not have all of the advantages of the truly self-directed Solo 401k it would be your option if you wish to have checkbook control over your retirement moneys. 

What other options do I have other than List Source, or should I just continue to build my own database?  

We will continue to allow it to build then buy more properties.