Have duplex and live in one unit-Cash out or Heloc, refinance ?

[Nazgul Tataeva]

Hello,

We bought a duplex 7months ago and living in one unit and renting other unit. Now, we would like to buy a house with a good school ratings and rent our side too. Market is hot now and I was thinking to cash out/HELOC refinancing the duplex, but my lender is saying "you can't because you didn't pay 20% of the mortgage yet".

FHA loan 10% down payment and loan amount $411K

Is it true or too soon to HELOC or Cash Out Refinance?