Others have given good advice for the current campaign so here is something to consider for the future. Diplomacy in the early game is worth wods of cash. Selling alliances to AI can net 1k+ Florins. I sometimes get 2k florins from trading alliance and trade rights with some factions but that's rarer. If you trade map info, offer your info in exchange for theirs and a few hundred florins. I usually get 400 per map trade even if it says maps for maps is balanced. More if it says map trade generous. I stopped trading map info with French tho in English campaigns as it seems to make 'em more aggressive (probably not a good idea to trade maps with your immediate neighbours unless they are puny).

I even got Timbuktu from the Moors once just for an alliance in an English campaign. I was so happy! Was expecting to fork over 10k after asking what they wanted (can get an early 10k easily as the English by sacking Edinburgh). Built a grain exchanged and popped out enough merchants for the gold and ivory in Timbuktu and Anguin which gave serious amounts of much needed cash.

The generosity of a deal and the finances of the faction will determine how much cash you can get out of the AI.