Do all mito kids experience lack of energy?

Hi.  I am Paula, mother to Audrey diagnosed with Mito this past April.  She has never experienced a lack of energy?  Is a lack of energy a common symptom with all mito kids?  Her main symptom is low muscle tone...she did not walk till after she turned 2 this April, her speech is delayed..has mostly vowel sounds, but does communicate and gets frustrated when you don't know what she is saying!  Typical 2 year old...She runs around like crazy and often does not want to go to bed!  It takes a lot to slow her down!  I am not complaining...just curious...would love for someone to tell me...maybe they diagnosed her wrong.....but I know I am wishful thinking there...