Pregnancy scare

My partner (22m) and I (20f) accidentally had unprotected sex while I was ovulating early last week and I've been experiencing a few problems since then (tender breasts, very severe nausea and occasional vomiting). I'm not due for my period for another 7 days and I'm stressing about whether or not I might be pregnant and I'm ambivalent about whether or not I would like to be pregnant. We've had a few pregnancy scares this year and each time that I find out I'm not pregnant I get really depressed, I'm emotionally ready for a baby just not financially and I'm worried about what my reaction may or may not be when I find out.