What am I missing in my dishes (Indian Cuisine)
The main reason why you are not getting the flavorful spicy flavors you expect from Indian Cuisines is not because of the quantity of your spices but rather the variety and quality. 

Most Indian dishes will have much more than just chili powder and turmeric powder. Many dishes from this cuisine will contains different mixtures of: cardamom, ground peppercorn, chili powder, turmeric, coriander, cumin, fennel, mustard, nutmeg, allspice, tamarind, cinnamon, cassia, garlic, star anise, and cloves just to name a few.

Often times all of these ingredients are whole and ground into powder at the time of cooking to retain the maximum flavor. After the spice has been ground into a powder it loses its flavor as time passes. 

A common technique to help release the aromatics from these spices is to heat up and toast the spices in the pan beforehand.

If you don't have the time or the money to deal with all these fresh spices, at the very minimum you should try to buy curry powder rather than turmeric powder at the store. Curry powder typically contains a spice blend that includes turmeric and few of the other spices I listed above. Ingredients of curry powder will differ from brand to brand.

I am unable to help you with how much spice to add to a dish because it varies way too much upon what type of dish you are making and personal preferences.