possible

well I used web MD to help recalculate my cycle because is tarted spotting with light cramping. my cycles before using the app were 35 days long well if I start today would make it 30 day cycle. and if so according to WebMD my fertile days were the 13 through the 18 and I had sex the 16 and 17 last month. it could be implantation bleeding. I am so anxious and hopeful. anyone else deal with this too? seems this apps calculations aren't 100% but what is lol.