Do my symptoms mean cancer?

Hi doctor,

I am a 24 year old female. I had an anal fissure a few months back due to constipation and it got healed with medication. For a week, I have constipation due to the change in my diet and lack of water intake. Whenever I had a bowel movement, I would get some prickly sensation in the anal area and itching. Two days back, I saw some blood and very tiny blood clots in stool. I took the same medicine, which was prescribed for anal fissure. My doctor told me to take the same whenever I had a fissure again. I have been taking that medicine for the past days and I did not see any blood or blood clot in the stool. The stool appears normal in texture and color. But still, when I pass motion, I feel a little swelling, slight pricking and itching in the anal area.

Today, I read something called colorectal cancer or tumor. It has confused me. Many links say that the blood in the stool is the first symptom, there is a lot of bleeding and sometime bleeding cannot even be seen with the naked eye. Which is the truth? If the bleeding cannot be seen does it mean I still have a tumor or cancer in the rectal area? They also added up a lot of other symptoms like weakness, etc. I do not feel any of that. Apart from this, I am extremely healthy. I do not smoke or drink. My exercise includes yoga and dance. There is no history of cancer in my family as well. I am scared after reading that. I think even my normal appearing stool could have blood in it and there could be a tumor. I feel there is a little swelling or obstruction in the rectal area. I would like to go for colonoscopy. Will they do a colonoscopy to the patient of my age? I want to know whether my doubts are correct. Do my symptoms mean cancer?