If implantation bleeding happened when period was due ,how long should it take to get a BFP?

Ok I thought I may be pregnant before AF was even due on the 8th of this month...had early signs,nausea,tired,emotional,very sore ies,hips ached,headache,hungry all the time,very very thirsty,watery mouth,peeing more often,uterus sensitive if I leaned against the sink,etc. So due day came and went,next day spotting. Cried ,thought I was starting,but flow never came,just very light watery red tinged blood and sometimes brown old stuff instead....this went on off and on for 4 1/2 days.So I called my doc.and she said maybe implantation bleeding,may be ectopic pregnancy,or miscarriage,and to wait to test.Says I may not get a pos. til next AF is due. So,how long should I have to wait? I really need that confirmation even though I feel pregnant already! And,I can't afford blood work or ultrasounds,my insurance hasn't went through yet,what should I do?