How normal is it for your cycle length to fluctuate?

Clare • Sun, Sep 08

I got off birth control about 4 months ago and now we use both condoms and pulling out. But my cycle length is usually 28 days every month when not on the pill. Now I'm 3 days late and this morning I started to notice a little bit of brownish-red blood when wiping, but I'm still so nervous. Is it normal to fluctuate by a few days within a cycle?