Sounds like fun. I sometimes wish I remained in the middle ages for a millenia or more. Knights and Pikemen are cool.
Anyway, you probably need to switch to a better government if you are still a despotism.
2. Start over, but on your next game:
3. Read the manual.
4. Learn to use the different interfaces, particularly, the city screen and your domestic advisor. With the domestic advisor, you can adjust the science rate if your economy is strong enough.
5. Build roads everywhere. Most squares will not produce any commerce without a road. Without commerce, you will have no science.
6. Play again and then ask more particular questions, and the answers you get will be far more helpful.