do you think I could be pregnant

Hi I would like to know if I am pregnant.
I had been on the depo for 6 months I should have got my last shot on the 19th july I then went and got the pill but keep forgetting to take them. I have been having slight symptoms like head aches, heart burn, sore lower back, twinges and cramps abit light head every so often o and tingley boobs . O I had my period on the 15th august had sex on the 20th last day of period I had a very tiny bit of mucus with brown blood on the 26th do you think that could have been implantation bleeding. O and I have taken some pregnancy tests but they have been negative as it is to early to test. I did have sex more than once this cycle just it was the next day I just felt odd. I would really like everyone opinion. I have also had two other children and I did get pregnant both times on the last day of my period well Im 99% sure I did anyway

Edited by megz

Megz, the the tiny bit of mucus with brown blood might have been from ovulation,  from what I worked out, 26th August was day 12 of your cycle...

Its common for me at the end of my cycles to have the brown tinged discharge, I always just thought of it as the cleaning out of it all