Because your sister was diagnosed with Ovarian Cancer
,you too have to be investigated.
Increased frequency of urination may be due to Urinary tract infection
.Pressure in the vagina may be due to infection in it or from surrounding structures.
,Right Ureteric colic and Right Ovarian pathology has to be ruled out by routine investigations like Ultrasound
Consult your local doctor.
If you review with reports,i can clarify further.
All the best.