Question re: i-1864 3 years tax returns

Hello 

Background

I came to the UK on a work permit and since married and have Indefinite Leave to Remain. My DH and I have decided to move to the U.S. I have worked on and off and didn't file taxes (I know stupid mistake) I have now filed taxes for the time I work.

Question

We sent in the I-130 petition, and premium police certificate request today. I sent my taxes to U.S. Do I have to have 3 years of returns to for the (I864) interview? What is considered acceptable copies? Would I need to request a copy of a filed return?

Thanks in advance.

I found the answer. I filed my taxes. I can request transcripts from the IRS after my returns are filed.