This summary has a list of "warning signs". I'm surprised that your doctor doesn't think it's time to remove the portacath, which is a straightforward procedure.
I've read about people keeping portacaths for years, but 9 years seems like the upper end of the scale.
This fact sheet from the MPS Society says "Most surgeons say most ports will last anywhere from two to six years."
Another site advises that "Your port may stay in place for as long as it functions correctly, or as long as your doctor determines that you need it." If you don't think yours is functioning correctly, then I think your concern is warranted.