It doesn't hurt to get it checked out, but I don't think you have much to worry about. An ultrasound is really good at detecting solid masses, and it appears you don't have any. If the lump has always been there and hasn't changed, it's not cancer. Cancer doesn't sit around for 14+ months. However, if it changes in any way, you should have it checked. You can have it checked to put your mind at ease too and find out exactly what that lump is.