Matlab is a fine first step for becoming a software developer. I used Matlab in all my courses for Control Systems, Communications Systems, Signal Processing etc. So if Matlab is all you got, then that's great!
The toughest part about learning to write code is to learn to think algorithmically. C/C++/Java/etc all have the same basic syntax.
I have a Computer Engineering degree, so I don't exactly help my argument here. However, I know for a fact that ALL engineering students (and math/physics/chemisty/etc) at my school, regardless of major had to learn C++. Mandatory.
Regardless.... you can always sign up for a programming course. In fact, to be an expert programmer, you need 2 courses:
1. Intro to C/C++
2. Data structures.
That's it. You can easily pick up Java or any other language in less than 1 month.
Just think about it. There's no excuse for not knowing how to write code. Just do it!!!