Just wanted to provide everyone with my update:
Overall I had a very pleasant interview experience! It was indeed a combo interview. I came into the building 30 minutes sharp before my appointment. The security officer at the door didn’t even ask about my husband accompanying me, but I still told him I had a pending i751 application. My husband was allowed to come in and be with me throughout the interview. I checked in and then waited about 15-20 minutes to be call for my interview. First, the officer asked me a few simple questions about my i751 application to confirm our personal details, address etc. Then he moved onto the n400 interview. He started it off with the civic test, then the reading/writing test, then he asked me the Y/N questions in the n400 application. After that, he said I got approved! The whole interview took about 20-30 minutes. Then he said I would receive a letter with oath ceremony date soon in 2-3 weeks. Here I told him that I wouldn’t be able to travel out of town after mid march as I’m due to give birth very soon (I live really far away from Dallas area so I’d have to either fly in or drive for long hours). He then told us to wait as he tried to get my i751 application transferred to him so that he could approve it as well as my naturalization interview right then. We waited for a couple of hours, and boom! My i751 got transferred to my officer in time for him to add me to the oath taking ceremony in the afternoon! Of course I gladly took it!! So the whole process from submitting my n400 application to getting my oath ceremony done took about 6 months. My husband and I were both extremely happy. We were there in the building from the morning until 3pm - tired but it was so worth it. I’m so grateful that the officer was trying his best to assist my situation. Overall my whole experience at the Irving office was very good.