I have a large lump on the tip of my cervix that has gotten larger over the last year. The opening to my cervix is getting bigger. What could it be?

See GYN. you must reporting what your GYN told you,otherwise how you can tell what is in your cervix. either way trust your GYN,and follow their advises. the lump could be a polyp.tumor,benign,rarely malignant,pap smear,punch Bx will clear that. the opening of the cervix depend on your time of the cycle,unless you are trying to get pregnant,or you are pregnant ,the opening of the cervix is not important.
Cervix. Visualization of the cervix is best carried out with the use of a speculum during a vaginal and pelvic examination and your gynecologist is best qualified to evaluate and advise you about your findings.