Am I pregnant?

Hello,

I have a few questions and I’m quite nervous. So my boyfriend and I have been together for almost 4 years and I am now almost 4 days late on my period. I feel very different, my weight is fluctuating and i feel like I have to pee constantly, I’m also getting severe dizziness and nausea what does this mean? I was suppose to start the 22nd of this month and it is now the 25th. Please respond quickly I am in need of answered. (My grandma is also picking me up a couple of pregnancy tests) when Is a good time to take those?