I think A- grades are great and you don't have to get straight As to get into grad school. I think that an A- average is a strong GPA for applications.
In addition, I remember that Complex Analysis was not even part of the Physics major at my undergrad, but it was a recommended course for those interested in grad school.
Are you taking any more math courses? I remember my Differential Equations sequence split the ODEs and PDEs into two separate courses. I also remembered taking a statistics/probability theory course and there was a 4th year mathematical methods on how to solve things numerically. At my undergrad, there was also a 2nd year level course that basically taught you how to use CAS software such as Maple and Mathematica. My GR theory friends make extensive use of GRTensor, which is a package for Maple. Maybe you have covered all this in your CS classes though!