I been constipated spotting and urinating a lot more in the last week my period is 8 days late I had sex on oct 26 but I used plan b I took home test it's negative

Plan B can throw of your period. Read the pamphlet that should have come with the pills, it will explain the symptoms you may experience from taking this medication.

Agree, had you read the information that came with the plan b pill, you would know every sign you said are expected side effects.

That does not mean you are not pregnant, plan B is not 100 percent effective and less the longer you wait after sex to take it.

So best to wait till next month and see if the period comes as normal