Unlawful Presence and Overstay I-94 Expired, I-130 Approved

Hello everyone,

I got married in 2015 with a green card holder and in 2016 june i entered legally in usa with b2 visa! Aug 2016 we applied for i-130 and in nov i got approved! Dec 2016 my i-94 expired and i didn't exit the country because i got pregnant so we decided it is better for us like a family to remain here and continue with my application. In june this year i delivered and now, september i got a letter from uscis saying that i have to get ready for my green card interview but in my home country!
As far as i know, i overstayed and i already have a 3 year ban!

My husband will become us citizen after 2.5 years. What do you advice is better?
I was thinking to go to a lawyer and ask advice, maybe they can help but on the other hand i keep reading posts that lawyers they just wanna take the money.

Can i apply for a waiver? And if yes, can i continue staying in usa and than wait for my priority date?

I'm confused because there are so many information abt this case.please advice if you know.

Thank you so much

Unlawful Presence and Overstay I-94 Expired, I-130 Approved