My guess is you have been called as they doubt your intention of marriage for reasons such as a hasty wedding, few witnesses, no honeymoon (initially) and yes the lawyer's statement that you will have a wedding reception but did not have one.. You should have asked for your CAPS notes which would have helped you better understand the situation but what's done is done.
Make sure that your's and your spouse's story match... give them detailed understanding of "work commitments" . State facts as much as you can as they dont reason much with emotions or sentiments. Above all be confident, talk straight to their face, show that you really care for each other. Take evidence of communications that you guys are having pre and post marriage (emails, bills and whatever you can lay your hands on). The fact that she has visited you after marriage is a good sign...
This forum has a section where possible interview questions are listed but my guess is that they will question you more on your wedding and aftermath....
I hope things go well for you..do let us know how the interview goes..Best of luck