Did I apply BRRR strategy wrong?!

[King Phinyathanabat]

I have 2 rental single family houses in Cincinnati that I own out right. One i have it for 2 yrs and 1 yr for another. I tried to apply for loans with assumption that i have 2 years of experience and I might be easier to get a loan to get my next property. 

I was about to make an offer on my first multi-Family, and waiting for pre- approval letter from a loan company that i thought it would go thru after i have tried 10 different banks.  Unfortunately, they turned me down due to debt to income ratio is high. 

I thought if i have high equity on the property i would get a loan pretty easy regardless of my w2 income. I don't know what should I do next??

I invested in the 2yrs property at 40k and i can sell it at 110k, Should I sell it or keep renting it at $850 ($400 cash flow/month) ?.

I invested in the 1yr property at 50k and i can sell it at 85k, Should I sell it or keep renting it at $850 ($300 cash flow/month) ?.

I have 20k cash, should I pay off my student loans off so i can reduce my debt to income ratio? but then i will have no money down.

Any advice would help, 

Thank you