Brief Answer:
Please consider following conditions

Detailed Answer:
Hello
i had gone through your question very diligently and i can understand your concern

Green colour stool at your age could be suggestive of any of following
gut infection
Liver and gall bladder disease
colon carcinoma

I would like further information to help you better like
whether you are having any pain in abdomen or cramps
any recent change in your appetite and weight
are you diabetic?

since bowel movement are normal so in absence of other troublesome features, I don't think its bothering you much but you need to concerned until diagnosis confirmed

in my opinion I would advise you few investigation like blood for hemoglobin CBC Liver function test and a stool test for occult blood
if it persists you need a endoscopic examination by a gastroenterologist

have plenty of fresh fruits and steamed vegetables
have lots of water and fruits juices
have ORS to counter electrolyte imbalances

Hope this answer your question
waiting for your reply
best wishes

---

Brief Answer:
worm infestation or mal absorption like steatorrhoea

Detailed Answer:
Hello
since your bowel movement is normal and there is no vomiting or pain in abdomen, it rules out the gut infection or enteritis

this could be due to indigestion and mal absorption like steatorrhoea or worm infestation
I would advise you to get stool test for ova cyst or protozoa with occult blood or fat

have plenty of water and fruit juices
have fresh fruit as whole and steamed vegetables
keep your diabetes check regular and under control

Hope this answers your question
regards

---