Possible implantation bleeding?

I had a slight watery pink discharged on the 25th day of cycle, then light bleeding on the 26th day. I thought it's my AF. The light bleeding is red and brown in color and it takes up around a "watch face" size of area in my pad. Today is the 27th and the bleeding stop. I usually have 30 days of cycle. Could that be a possible implantation bleeding? If yes, is there any success rate after having that size of bleeding and not the normal spotting? I understand that I should only take the pregnancy test after I missed the period. Now its still early, anyone can advise? Please help.. Thank you