A speech impediment can consist of repetition, which can be part word (C-c-can I...) or whole word (Can-Can-Can I...) repetition; prolongation, where a sound is prolonged (Ssssssso as I was saying.. ); and blocks [no sound]. Not every speech impediment is the same, it sounds to me like yours consists of full/part word repetition and blocks more than other types, which is perfectly normal.