I dont know what to do

Today i am 2 days late and i tested this morning and it was definitely a bfn no second line at all. But im still showing no signs of getting my period i usually have light bleeding im extremely moody everyone can tell when im pmsing cause i become a huge bitch. I have some early pregnancy symptoms im just so confused and scared im only 18. Should i wait and restest if i dont get my period in a few days or is it just getting in my head maybe like a phantom pregnancy.