Thanks for your query.You have not mentioned your age in your query.Based on the facts you have narrated it appears that you have increased frequency and urgency . These symptoms are not related to you sexual fantasy.You have to get following investigations done before you plan for Endoscopic Examination of bladder.
1) Routine Urine Test
scanning of abdomen to rule our enlargement of prostate
3) Urodynamic evaluation of Bladder and urethra
These investigation will help in concluding the reasons for your symptoms Consult some Urologist
for clinical examination and-further treatment..