Suggest Remedy For Delay In Periods

before I took contraception my periods was regular I was on contraception for 3 years I came of the implant this January my doctor said wait 4-6 weeks and hopefully thats when my cyle should come back it came back exactly on the fourth week and lasted for 3 days like my periods use to, my period was ment to be due this month on 19th of may I am now four days late ive took three pregnancy test all negative my breast hurt and also have whitey brown spots around them I hav headacheas known and again and pains in my vagina but no discharge and dont feel sick how long now should I wait to take another one and could I be pregnant