Mixed symptoms Decidual Bleeding or Miscarriage?

About a week before I was due to get my period I had weird symptoms, light cramping, complete exhaustion, tender breasts, hunger, gas, etc. I dont get any PMS symptoms, except for acne, and so I thought I must be pregnant since I had unprotected sex during the middle of my cycle. Then, I became nauseaous and a day later got my period with normal during period cramping. However, there is a lot more brown and it is lighter than usual, not a LOT lighter, but definitely noticable. My first thought was, because I suddenly was very nauseaous and the cramps, etc. was that I must be having an early miscarriage, and if not, then I was having one hell of a hard month, I usually have fairly symptom free periods, so I knew something was off. Am I right in thinking this is a miscarriage? The lighter than normal period is definitely strange along with the nausea. Ive been trying to have a baby so a part of me keeps thinking "decidual bleeding" but of course that is probably not the case.