骄傲 is completely correct, you can use 骄傲 in this situation, it won't bring any negative connotations.

In some situations, 骄傲 really means arrogant, for example, "This guy is so 骄傲", "这个人很骄傲".

Below statements fulfill "Mum is so proud of you":

妈妈为你感到骄傲

 

妈妈为你感到自豪

 

妈妈为你感到光荣

To be more emphasize, you could use "无比"，it is like incomparable, for example:

妈妈为你感到无比骄傲

 

妈妈为你感到无比自豪

 

妈妈为你感到光荣无比

骄傲 is completely correct, you can use 骄傲 in this situation, it won't bring any negative connotations.

In some situations, 骄傲 really means arrogant, for example, "This guy is so 骄傲", "这个人很骄傲".

Below statements fulfill "Mum is so proud of you":

妈妈为你感到骄傲

妈妈为你感到自豪

妈妈为你感到光荣

To be more emphasize, you could use "无比"，it is like incomparable, for example:

妈妈为你感到无比骄傲

妈妈为你感到无比自豪

妈妈为你感到光荣无比