Is it normal in your country/culture/social group not to have much experience cooking? I had a lot of second-hand experience by the time I was 18 from simply watching my parents or other adults, and sometimes being asked to help.

I have some pretty basic recipes I cook if I'm a bit tired from work, I can make them without really thinking (e.g. diced chicken + green beans & cream + pesto.) Fortunately, the nearest shop is about 2 minutes detour from my route home, so I can wander in and buy the things I'm missing.

3 months isn't a long time.

I think one way to build up intuition is to cook a recipe with a very short list of ingredients multiple times, with small variations (like the size of cutting things up or cooking time or whatever).

One thing Good Eats consistently does is talk about whether an ingredient has a functional purpose in a recipe, and what that purpose is. Other cooking resources do that too, but usually not as well.

This right here is exactly right. If the reasoning is mentioned at all, it's usually incidental and not intentional. When we talk about salt in the seasoning step of our pan-sautéed chicken lesson, we wrote: "Salt "brings out the flavor" in chicken by reducing our perception of bitterness in foods. This, in turn, leads to an increased perception of sweet, sour, and umami (savory) flavors."

This is obviously a rather trivial example, but hopefully you see how generalizing this (and similar nuggets of information) can help.

You can see the link to my site elsewhere, but I'd be happy to help more thoroughly if you're interested. The ability to do this is not a reflection of your ability to think creatively but rather that you need to understand why you're using certain things and what effect they will have on your dish.