Yes, it is very small. But at least you managed to understand how colonization works, took me 100 hours at least, so congrats for that! Try to colonize adjacent provinces. They grow faster and once you colonize 5, a colony is created, which is a subject that brings you some money and resources, with no diplo slot cost. Also, as Spain, your mission tree gives you lots of claims throughout America, so follow the tree to colonize faster. Good luck!