My period.. questions!?

yesterday i started my period for the first time and it bled lightly for like 2 hours then it stopped bleeding around 6 for the rest of the day. Then today its bleeding lightly like really light. But im worried cuz my back feels tight and im kinda tired and drowsy. And its my first time so i know its gonna be all funky and what not. But why isnt it bleeding heavy? I dont get it. All this is getting to me, what if theres something wrong with me? and its blood but kind of light redish gooish blood. Please help!