Shorter and lighter cycles

Hey ladies! I've been TTC for some months now (stopped pill in January and started charting in May). Still not preggo however lately ( last two cycles) I have noticed my cycles are a lot lighter and slightly shorter. My am fairly regular and they used to be 5-6 days. Now, about 3. Has this happend to anyone else before? Not sure if this is a sign that my body is preparing for pregnancy - but that may just wishful thinking. Lol. Anyone else have this happen since TTC? Please share. Thanks!