Scared and stressed

Saralynn
This is my second pregnancy. My last, almost four years ago, resulted in a miscarriage at 12 weeks. We have been trying to get pregnant since and had given up last year and decided to pursue adoption. Surprise suprise, I'm pregnant. I couldn't be more thrilled but I'm scared out of my mind. I started spotting, really lightly about two days ago. It's not every time I go but every time I use the restroom it's an stressful endeavor. I'm not sure if I'm miscarrying or if this is normal. 
I'm wondering if anyone else has had similar experiences? Any idea, when its in the first 6 weeks, how much light spotting is enough to be concerned about? I'm just freaked out a little and would appreciate any support or guidance- thanks !