after a miscarriage

So I had an early miscarriage at almost six weeks. I had the miscarriage November 20th and stopped bleeding on the 23rd. It's now December 26th and I have had cramping since December 20th but no bleeding. Yesterday I had spotting when I wiped and again today but just once. I'm not sure what's going on or when my cycle will return to normal. Anyone else have a similar experience?  How long do you wait before you become worried?