Is there a such thing as a false positive???

I feel like I'm losing my mind I see it but find it hard to believe it! We have been trying for so long, could it really be this is it! I have been crying since I took the test. All tears of an overwhelming Joy! Usually when I'm crying at this time of year it's because this is the same date I laid my 16 year old boy to rest 3 years ago. I didn't expect anything but tears of sadness today until I took these tests! I can't believe my eyes, I can't believe it's really real and the joy I'm feeling inside at this very moment!!