Late periods, Pregnancy test negative

Hi there,
I'm 19 years old and I am really late in my periods. I was supposed to get them a month ago, around june 18th. Today it's July 16th and still nothing. I had protected sex with my boyfriend around beginning of june even though i don't take birth pills. I did a pregnancy test two weeks after i was supposed to get my period, on july 2nd. It was negative.
I think the test was pretty accurate because i didn't do it too early and respected the notice. But i guess we never know. I don't have any pregnancy symptoms. But i'm still worried about not getting my periods and I was told it was safer to do another test.
I will soon. I just wanted to know if there's other reasons maybe causing my period getting late. I had final exams for uni at the beginning of june, i was pretty stressed. Could it be a reason. Could i still be pregnant even if the 1st test was negative?
Thank you

[claire5522]

If you are on the pill and used protection and had a negative HpT you are not very likely to be pregnant, infact it is almost impossible.

Stress, change in diet, change in lifestyle can all influence our periods, amongst other things.  Talk to your doctor if it doesn't arrive, he/she may be able to give you something for it to help it along.

[watercolours]

I'm NOT on the pill put did use protection.
Anyway thank you for your response.

[claire5522]

Sorry I read your question incorrectly.  Even though your not on the pill unless the condom ripped or came off the answer remains the same