It is not Implementation bleeding. It is known as Implantation bleeding. Implantation bleeding occurs 6-7 days after ovulation. Ovulation occurs on day 14 of the cycle. Your last period date was 17 April. Your sexual relationship date was on 7 May.  That was much after your date of ovulation ( your ovulation date would have been 1 or 2 May). So there is no question of conceiving if you have sexual intercourse 20 days after the date of last period. However, to be 100% sure you can get beta HCG level done after 5 days.

Consult for discussion

Please consult for proper discussion.

It's difficult to differentiate these two conditions based on type of bleeding.

Emergency pills are known to cause irregular vaginal bleedin Wait till the expected date of periods