My first period with a mirena coil lasted something like 6 weeks, but most of it was very light. It gets better though.
After the first four months of erratic bleeding I didn't have another period until it was removed, no spotting, nothing, it was great.
I took mine out after a few years because it was awful for my mood, worse than I realised until it was out and I felt the difference within a couple of days.
For bleeding control it was incredible, my 200ml monthly flood stopped happening, the NHS says 30ml is average and 80ml is classed as unusually heavy!!
For me 80ml would have been incredibly light, that was the only reason they fitted the coil at all.
If you're tolerating it from a mood point of view then I'd say everything is going well with it.