Im 12. i have ocd from what i can tell. i cry over this sometimes. what do i do?

i havent told my mom and for some reason i dont want to. i dont know why. i am constantly praying under my breath the same prayer: and thank u so much Lord u r awesome mighty and holy and im sorry lord in Jesus name i pray amen. or just :in Jesus name i pray amen. it drives me crazy and i also have to count the numbers on a clock. this is ocd right? what should i do. (please no comments about my faith) im crying so much please help. ( when my friends ask what im saying under my breath i tell them im singing to myself) is this a bad thing that i do not have meds for it? can it do brain damage or anything? im crying im so scared please help