I have most of the S america and some N america but not that insane income. How did you spread your merchants?
The key while you are waiting for colonies is to absolutely dominate Sevilla. None of your colonies mean anything if you are not taking the vast majority of the Sevilla trade.
So take out all the Morroco and Algiers provinces in the trade zone. There are two of them that give the +5% trade power IIRC. Prioritize building + trade power shit when you have diplo points to spare. Don't take any decisions that decrease trade power.
For merchants, in order of priority: Sevilla, Genoa, Ivory Coast, Caribbean. For colonists, work a chain towards the Caribbean and then get all of those nice 5-7 base tax provinces. Get some Ivory Coast so you can put claims on the natives. Do not worry about North America, it is useless.
Push Ivory Coast trade to the Caribbean not to Mauretanian Coast.
Dominate Sevilla with your merchant fleet. I think I have like 26 light ships in Sevilla haha. Send around 10 light ships to Genoa to try and leach as much as you can. Depending on how Ivory Coast is looking in terms of trade power you either need a large merchant fleet or you need to send in the Conquistadors.
In my game, I have no competition in the Caribbean since it is just me and Spain there, pushing to Sevilla. All of the Brazil trade gets pushed to Ivory Coast by default, then Ivory Coast pushes back to the Caribbean. The rest of South America gets pushed to the Caribbean. In my game Spain has most of this but I am reaping the trade money haha. In my game I also have colonists in Zanzibar and Gulf of Aden pushing around the horn of Africa. The New World stuff is more lucrative by far for me atm.