Testicular Cancer Concerns?

Hi, I'm 15. The last few days I have been noticing something weird. In Ed cl they talked to us about doing monthly exams of our testicles to check for bumps which could be cancer. Well I did one, and I noticed a SMALL bump on the bottom of the left testicle. I also notice that my left testicle seems to be a bit harder then my right one if you can understand that. I have my yearly physical at my doctors office in 2 weeks so I will talk to her about it then. Part of the physical is checking for bumps to so she should notice something.