Their father agreed to pay cash for it and my friend and I are now paying him back over the course of 6 years.

If you can afford to hang on to it, do some value add and be okay with less than ideal cash flow for the first few years, you should still do fine, but most people want that instant cash flow.

Particularly buying properties to rent out for additional cash flow but also flipping properties.

Are you cash flowing the property?

Pay your house off then only buy investment properties in cash. 

@Edison ChadwickThere will be cash flowing deals you will have to deploy more capital to see cash flow. 

All without using a penny of my own cash.

Some lenders can refinance a hard money loan after 3 months of seasoning / waiting and use the new appraised value if the borrower is looking to pull cash out for a new project. 

The problem is, the vast majority of the SFHs currently available, both on market and even off market, do not work when looking at the numbers if you want positive cash flow.   

I am wanting to sell all my stocks and just take the cash since I don't want to drain the majority of my savings/checking purchasing real estate and have most of my money in stocks.