c++11 - regex matching

I am extracting info from a string using regex.

  auto version = { // comments shows the expected output
    "2012.12",         // "2012", "12", "", ""
    "2012.12-1",       // "2012", "12", "", "1" 
    "2012.12-SP1",     // "2012", "12", "SP1", "" 
    "2012.12-SP2-1",   // "2012", "12", "SP2", "1" 
    "I-2013.12-2",     // "2013", "12", "", "2"
    "J-2014.09",       // "2014", "09", "", ""
    "J-2014.09-SP2-1", // "2014", "09", "SP2", "1"
};

The regex I have is the following:

    //                  J   -  2014       .  09      -  SP2      -  1  
std::regex regexExpr("[A-Z]?-?([0-9]{4})\\.([0-9]{2})-?(SP[1-9])?-?([1-9])?.*");

and this seems to work well. I am not very confident about this since I don't have much expertise in regex. Is the regex right and can this be improved?