3 weeks pregnant

First time mum please help 🤣

I found out I was pregnant this weekend and according to the tests I'm 1-2 weeks. However according to my period and online due date calculator I'm 3 weeks. The last week I've been really uncomfortable with my belly and very bloated I can't seem to get comfy. My boobs are also so painful and sensitive. And I'm constipated Is this normal? Surely it's too early for symptoms? Also has anyone else used clear blue tests. How accurate did you find their dating?