Is It Possible To Abort A Pregnancy Without Doctor's Intervention ?

hello doctor,i am 18 and we played on 20th jan..but didnt do any sex...after that i got my periods late for first time in 7 years..its was heavy flow for 3 days then suddenly stopped and some brown discharge for next 2-3 days..i had 3 urine pregnancy test that time all came negative..last test i took was 6feb,and also ultrascan but nothing found,now i feel bloated and my nipples tip have some burning sensasation but breast not paining,last period i got was on 8 feb,dis time too i am not getting 2day its 7 march.should i again take test? i dont want to b pregnant,if its positive can i abort without any doctor consultion?plz reply.