Haven't got high yet?

So 2 weeks ago, I tried weed for the very first time, I smoked a joint before school and had around 4-5 hits but I didn't feel stoned or high, I only felt like headed. So a week later, I tried to smoke it again but in a bong, however I didn't get high, I just felt light headed again.. Anyone know why I didn't get high? I still have some weed left but I don't want to waste it.