Faint to Dark

So I'm 4w preggers and a complete spaz lol I'm so anxious for my first OB appointment which isn't till January the 14th. My question is,when I started taking tests (not counting the digital test that said I'm 2-3 weeks) the lines started out faint and have gotten darker,I'm assuming that's a sign that things are going being there is more HCG is my urine? Any advice/info to ease my mind would help lol Thanks ladies!!