My doctor told me that if I had cancer that it would not be painful. I am a stubborn woman and I believe that if it gets big enough that it can press on things and cause pain

I'm not sure what being stubborn has to do with this, but what your doctor was trying to say, I believe, is that many people who have cancer are asymptomatic. Meaning: most people, depending on the type of cancer, location and severity, do not experience symptoms. In other words, it is important to know the "warning signs" of cancer, as most times cancer does not provide a "warning" with any painful symptoms. (For example: early-stage skin cancer is not painful, but a "warning sign" would be a new growth or discoloration on the skin that is unusual in appearance). Individuals can not rely on "pain" as an indicator of cancer, as by the time someone experiences pain from cancer, it is likely more serious, has spread and is more difficult to treat.

Of course, if cancer is allowed to spread (metastasize), is not diagnosed early enough, or is severe or in certain location(s) within the body, then the person could have noticeable painful symptoms.

I'm curious how this conversation began with your doctor in the first place, and why you don't trust him/her to tell you the truth about cancer and associated symptoms? Do you have a possible cancer diagnosis, or a family history of cancer that you and your doctor are keeping an eye on?