Period or pregnancy?

I'm now 7 dpo, my boobs are so sore I have really bad heart burn and my tummy feels like there is light cramping like it would be before a period, it's been like this since ovulation? Has anyone had symptoms
Like this and been pregnant or am I just convincing myself? How soon can I take a pregnancy test? It did say on my calendar to take it at the end of the month which is Friday? I'm not due on until next week