I understand your concerns. Since you have taken the pill on the 24 th may which is around 72 hours after the act so it should be ok as the pill can be taken up to 72 hours. There is no reason to worry. Your symptoms are not related to pregnancy, it s mainly due to anxiety.
In regard to the last part of your question, yes it is too early to get a home pregnancy test as after 6-7 days after ovulation HCG levels are seen in urine although the quantity is very less.
So I would suggest you to wait till the next period on the 8 th , and if you miss it then , you could get a home pregnancy test. Hope this helps.