3 positive tests, is it safe to say I'm pregnant?

After over 6 years of struggling with infertility issues, I've finally gotten my first ever positive pregnancy test results. I honestly never thought I'd be a mother, though I've always dreamed I would. I'm a liitle sceptical about the tests legitimacy so I've taken three tests the last three mornings, all positive. I have an appointment on the 12th to get blood work done, but I'm dying to tell at least my mom. Is it safe to say at this point that I am definitely pregnant? Or should I wait for doctors confirmation? Are there any other possible causes for a positive test result?