Did you work with any real estate professionals (agents, lenders, etc.) that you'd recommend to others?

Young professionals?

This is actually one of the main reasons many agents and investors may not like them generally speaking (they are often not serious professionals with a proven track record of success, the vast majority are struggling to find their first deal and are time-wasters to interact with).   

@Alex Del Rio welcome and congrats on Real Estate Professional Status (REPS) this brings with it a lot of tax benefits that you didn't have access to before.

Readers should seek professional advice.

Readers should seek professional advice.

Check with your lender and consult a tax professional to ensure proper structuring for interest deductions.

Lived in upstairs unit for 3 years, then rented both units out for the next 12 or so years Did you work with any real estate professionals (agents, lenders, etc.) that you'd recommend to others?

It’s advisable to consult with a tax professional or financial advisor to determine the most appropriate approach for your circumstances.

Assuming they were professionally prepared and compliant with state law, these should define your default interest terms – probably in your note.