Truthfully I think your game is going to be a stalemate and you should just start over. Don't consider that a failure of any kind, you have probably learned a lot during this playthrough!
Here are some general tips next time you start a game as Castile/Spain:
1) Colonization and Trade are your specialties and you need to exploit your early advantage in these - Castile is one of the only countries that benefits from taking Exploration as its first idea set. Focus on your early missions like conquering Granada and the North African Center of Trade, but during the early game, try to stay under the radar and build up your income base before you get dragged into difficult European wars with major powers.
2) Expanding in North Africa isn't critical and is a major drain on your Admin points. Take Centers of Trade and possibly a little bit more, but don't get bogged down there with major expansion - that is a classic mistake for a new player, and one I made myself on my first Spain game. If you can maintain a rivalry with Morocco, prioritize Humiliation rather than land conquest, it's just too expensive for Admin points compared to other things you can do.
3) Make sure you prioritize colonizing Centers of Trade in the Caribbean and in Ivory Coast, those are the gateways to the Sevilla trade node. In the Caribbean, that means the two COTs in Cuba and Hispaniola should be your top priorities before you set up a Colonial Nation. In Ivory Coast, that means you should colonize Gold Coast, eventually colonize your way to the inhabited COT to the east, and eventually conquer it. With those COTs, you will get an extra merchant and dominate one of the most valuable trade steering hubs in the world.
4) Colonize the Cape for the COT and extra merchant.
5) Don't overexpand your Colonial Nations. The bigger they get, the harder it will be to keep them under control. Focus on quality rather than just quantity - so aim to get all the COTs and Estuaries ASAP, make sure you rush to 5 total provinces to form the CN, and then slow down. You will eventually want to build up to 10 provinces to get the extra merchant, but after that, I find it's best to move on to other regions. Also, do not raise tariffs past more than 20% or so, Liberty Desire can get out of control fast when you have a big network of CNs (and you should!).
6) I think it's a good long-term goal to build up a trade route to India, Indonesia, Philippines, and China, but you don't need to rush once you secure Cape. Colonizing a few strategic, defensible lands is a good idea. (The COT in Manila, for example, or the various small islands linking Zanzibar to Indonesia.) Eventually you'll need to go to war to get the best lands over there but that's after you've set up a network of CNs.
7) Don't explore too much New World coastline! Drop off a set of 3 merc infantry led by a Conquistador in North America and then another set led by a second Conquistador in South America, and let them hunt for the Seven Cities. I find this to be the best way to find one or more of the Seven Cities of Gold.
8) Don't treat Portugal as an enemy by default. Remember that they steer trade back to your home node, too. And in the early game, if you ally with them and use them to fight Morocco, you can initiate wars and ensure that they don't take the land - which means you can maintain the rivalry (rather than eclipse them immediately), keep going to war regularly and Humiliating them, and profiting.
9) Make sure France and Ottomans don't get too large. On your map . . . Ottos are definitely too large. France you should aim to defeat and Humiliate on a regular basis, as well as release and dismember small pieces to keep them off balance, and break off any dangerous alliances they've formed. Ottos is trickier because you need to find the right moment when you have strong allies and are not already busy, while Ottos either don't have strong allies or are spent from a tough war. If Otto is rivaled and warring with Muscovy/Russia, this is much easier, but if you wait too long to start striking Ottos . . . well, the result is your map.
I could keep giving tips, and others will certainly have very different ones, but I think these set the early tone for the type of game I find enjoyable as Castile/Spain.