depo

hi in on depo and have been for over a year,i messed up abit in april,shot was due on 6 th and i had it on the 17 th,the nurse said i would be fine!! upuntill the 17th but extra protection needed after,2 weeks later i had brown spotting and was unwell so i had a visit to the doctor,i asked if i could be pregnant as i was worried and getting syptoms,he sed i wouldnt be preg as i was useing depo,no test were given by the doctors.i just had my last shot on 7th july along with a smear the same time,i thought the nurse would tell if i was but 2 days later i had bad stomach pains and lower back pain,so i went back to the doctors,the pain had subsided by this point,she gave me antibiotis and sed it was prob an infection,but now i am feeling movements...and worried i am pregnant,i dont really want to go back to the docs because they just say your on depo!! i feel silly,i have done home preg test witch was neg....please help very confused??