thinking too much

i currently have a full load of classes and under alot of stress. work school familily, it has me a little overwelmed. i know its nothing plenty of people have already been through. its just how i handle things. i'm a worrier, like my mother. guess i have that to thank her for! just what makes me tick,lol. well due to the sudden incline in the worry department i am thinking about dropping a class. due to the length of time since i've been in school and the importance of my grades i think this is the right choice; but now i'm wooried that i'm am rushing my choice. will this ever stop! i mean damn all i can do is my best and let the chips fall where they may. or am i worried because i really truely dont feel that i am giving my all? well i dont know! HELP! it feel like i'm under water, i can see the surface just can't make it there. any ideas?