Not enough income for conventional mortgage

[Daniel Green]

Long story short, my wife and I found a great deal on a duplex that would easily cashflow $600+ each month. After viewing both units and talking it over, we decided to go for it. However, when we talked with our lender we discovered we wouldn't be able to get a conventional mortgage because we didn't have enough income to offset our current mortgagSse + the duplex's mortgage. That thought never crossed my mind.. Newbie mistake.

We looked into private lending [our mortgage broker also runs a private money company], but didn't feel comfortable with the narrow margin we would have financially at such a high interest rate. So, for now, we are having our broker give us the max amount we can afford via a conventional loan so we don't waste time on anything too expensive.

My questions are:

1) Even if we do secure a cheaper property via a conventional mortgage, employ the BRRRR strategy and refinance a year later, won't we run into this same issue again?

2) If so, how do we avoid running into this problem without going to private money?

3) How are other investors able to purchase multiple properties using conventional financing without running into this issue? I'm having a hard time comprehending how this is being done without constantly increasing your income by $1000+/month each time you go in for another mortgage.

I'm quickly learning how naive I can be, but our experience with this duplex is raising a lot of questions I can't seem to figure out on my own. My wife and I are extremely appreciative of any advice you can send our way.