Could I finally be pregnant??

I have been feeling sick really badly for the past 2 days and have really sore breasts and I had really bay cramping and back ache, I ovulated about 8 days ago and me and my partner had unprotected sex 3 times while in my ovulation window my friend told me to wait 7 days and take a test, today I took a cheap strip test that I had from when we were trying for our first baby 2 years ago and it was negative but the dye looked it was running so I don’t think them tests are any good now, is it worth getting a proper test or should I wait a few more days or wait and see if I miss my period which is due in a weeks time?