Adjustment of Status - I-485

I went to interview today. We weren't seperated. We don't have many evidences to submit. We just have joint bank, lease contract, utility bills, and internet bills, pictures
The interview was smooth. He ask if that make sense to us that we get married after dating for 7 month( he said it is a little fast, so he ask if there is any other reason). We said no, because we love each other, and have same opinition in life. We answer most of them well. He copy some pictures, and ask me to annotate them. While i am annotating them. He asked my wife yes/no question. I was petitioned by my dad in 2016. I accidentally told him my sister is good for f2a, and i was too old for that. My sisters cam here in September 2018. At the end of the interview, he ask me again about my dad petition me. I said as i know that process was stopped since i got married to my wife. In general, i was comfortable to answer his question. He didn't ask us much about my spouse's family.
He said he need to review them before he decide. He said if he appove it, it will be conditional green card. Otherwise, he will ask for additional evidence, but he didn't give us any form to say our case is under review. He also said itI will take 3-4 weeks for us to receive a letter for them. I don't knoe what happened, but i thought we got approved on spot. Now, i'm very worry about it. Anyone please share your experience