Is Pregnancy Possible Within One Month Of Giving Birth To A Baby?

hi i have 8 children 7 in one relationship and 1 in my new one,he is only 7 months, but in the week he was born we had sex even tho i was bleeding,we have sex everyday , dont use nothing and we would like one more baby mad i no, and can work out why i havent fallen so done a ovulation test which came out positive so had sex day b4 and on the day i took ovulation test and day after and so on,i have been having loads of cramps feeling light headed done preg test looked like it was neg but then looked like very very faint line done test nxt day and that was neg, i started bleeding today but pain in my sides feel different,my breast hurt, headaches, please can u advice me wot to do im worried havin sex only days after the baby i have done damage, could i still be pregnant now and do a test 2mrw thank you