You may file a chapter 13 after filing a chapter 7. As long as your plan is for 60 months and you complete the plan, you will receive a discharge of any unsecured debt not in the plan. I would advise speaking with another attorney is willing to file the 13 for you.
To receive a discharge in a Chapter 13 after a Chapter 7 discharge has been ordered, you must wait four years after the Chapter 7 discharge to file the Chapter 13. Linked below for your reference is the applicable bankruptcy code provision, 11 U.S.C. 1328(f).
Your 2nd mortgage was discharged in your Chapter 7. The issue now becomes if you file a Chapter 13 now, whether you have done so "in good faith." What does that mean? Well, if all you intend to do in your new Chapter 13 is strip off the 2nd, you probably won't be able to show "good faith." You should have filed a Chapter 13 rather than a Chapter 7.
But if you have priority debt that you need to pay off in the Chapter 13, then the court can see that there is a genuine need for the Chapter 13 & will find that it is been filed in good faith.
I appreciate that this is a confusing answer, but this area of law is developing and the answers vary widely throughout the districts, even within the state of California.
Eric and Dorothy are correct. You must wait four years to file if you want a discharge, but there is no 4 year wait to file the 13 after the discharge of the 7. Sorry if I misspoke before.