Adjustment of Status - I-485

Hi guys .
I had my interview with my USC husband at federal plaza NYC end of April 2017 and still no decision. I-130 also not show approved after AOS interview day . Officer just said he have to review the case and give us a decision on mail for 6-8 weeks . But we didn't receive any decision yet. The interview questions was pretty much simple how ever my husband just didn't remember my mothers first name ! That made me feel so angry ?????? but the rest of questions we answered pretty much correct . And we had enough documents to show about our marriage. My question is , as we past the 8 weeks and it's almost 4 months after interview, Are they going to call us for second interview? Usually how long after first interview they ask for second interview? I talk with a lawyer on phone and she said typically if neede for second interview, they will inform you by a month or maximum two months after the first interview! Is that right ? What she just said is we just have to wait ....
Any idea why it's take too long ?
Thanks in advance and I wish everyone get their good news very soon !