Why is the loose leaf teas so watery?

I recently got into drinking tea and as I only drank tea bags beforehand (not liking them too much), I bought Keemun Xiang Luo leaves from a local tea house. Issue is, it tastes so watery. My mother believes this tea is unlike what she drank and loves it, but I cannot seem to taste the complex taste of the tea. I tried brewing it for longer and it was somehow simultaneously bitter and watery. I have to add mint leaves and a spoon of sugar to enjoy it, which is weird because apparently, high quality loose leaf teas are enjoyable without any additive??? I had also bought another tea called Min Lun Jin Luo or something but didn't try it yet as I am still trying to find out what's the problem with the Keemun.

Maybe my brewing method is the problem? I boil the water, put leaves (I think I put 6 ml of leaves in 600 ml water once because when I put more, it tasted way too bitter, but it may be because I had waited 5 minutes) in the bottom of a teapot, check if the temp is about 95, and pour the water in, and I experimented waiting 3 to 5 minutes, 3 being the best time as 5 minutes was way too bitter. I heard it's called "grandpa method" but I am not sure that was the issue.

I will try to make tea out of the Jin Luo thingy and compare the difference, maybe make myself a cup of the tea bag to compare how much different the high quality leaves are. Maybe I need to acquire the taste before appreciating the complexity of these leaves. Maybe I am overthinking and tea just tastes like that, but the fact my mother notices the complex notes of the leaves makes me think otherwise. What do yall think?