Ha...I instantly saw one of your many issues as soon as I opened the game. You are teching Currency in 800 something AD.
I'll be blunt here, you have a LOT wrong with your game...a lot. Not saying you need to move back to Noble since Prince is pretty easy, but you are making many many mistakes that are pretty much noobtastic.
First, take a look at the tech screen. See all the techs the AI currently have that you don't on the right. You should have all those techs in the BCs, especially Currency which is the most important tech in the game.
You are fight wars with just swordsman at 800AD on prince and the AIs will soon have Longbows and Maceman, all of which you are very very far away from. You don't even have Alpha.
Some points:
1) More focused tech path at the start. Get in the habit of getting the key worker techs immediately for food and strat resource. BW is always good to get early for whipping. Avoid unnecessary techs like Hunting, Archery and Iron Working which you can get in trades later. The exception is good Hunting resources nearby or tons of Jungles with Gems that you have to settle.
A good tech path here, without seeing the start, would be Agri>Mining>BW>POT>Writing>Alpha (backfill some junk)>Maths>Currency
2) DO NOT AUTOMATE WORKERS
3) Get to Writing asap via Pottery or AH based on what you need. Get a Library up, run 2 scientists to get that first GS asap and build an academy in your cap. Look to settle a high food location, or capture one nearby, to be your future GP farm and gear it up for that asap so you can continue running specialists for key bulbs and stuff. Have no clue what you did with the few GPs you popped.
4) Unless going total early annihilation, Writing should be in your first 4 to 6 techs.
5) On low levels like Prince, I recommend an Alpha beeline since AIs are slow to get it. Backfill the religious techs and any other techs you don't have. Get Iron Working and possibly Maths in trades, or tech Maths>Currency next, but get to Currency Asap. Trade judiciously though. Get what you can but don't unnecessarily boost your targets. If you play it right, you will soon not need AIs for techs as you will start blowing them away as opposed to getting blown away like you are in this game.
6) Get trade routes up asap. I don't settle cities without them if I can (via road, river, coast). Get foreign trade routes asap. You have none at 800AD. Trade routes are HUGE.
7) Scout
8) Learn to specialize cities
9) Build wealth and research as needed for a quick tech boost to get that advantage.
10) For the love of all that is holy, use Slavery
11) If you have horse nearby and want to go on the warpath, use chariots and horse archers. They are faster and more effective and kill on this level. Or if going with Swords, get it off well in to the BCs. Swords become less effective when you move up levels unless you use siege. I can't believe you are fighting with just swords in 800AD. that is brutal. YOu've only taken 2 cities and I doubt you take any more at this point.
12) Consider not focusing much on wonders for now.
Overall, if you are serious about getting better at the game you really need to totally rethink how you play it. Get more involved in the forum games and see what other folks are doing. Pick up tips.
Edit:Extra note - build more workers or capture some. Practice good worker management and again, DON'T AUTOMATE WORKERS