I... I just can't explain it. I was playing and focusing on science, I think I ignored happiness/city growth to long. Can't trade for any luxs since the allies only have one.
This game seems like a wash, but I had fun.
Much of your science comes from the population of your cities, so it is very important to grow your cities. If you are focusing on science, population is key to success. Happiness is extremely important to growth, so if you are trying for science, you need to get happiness as well.
Since GNK, there are so many things that can be built at any given time, so you really need to learn what is important, and what is not, based on your victory condition. As has been said, you should have all your cities at near population 20-35 by that turn. Your science should be near 700+, though your population is killing that. If you do go with lower populations, like sub 20, you need more cities.
This is a learning game. You won't be successful with it, but it might be possible to learn more from it and see how fast you can grow your cities. It is important that your cities are always growing as fast as they can, unless happiness is an issue, in which case, find a way to fix it. Trade luxury resources, get an ideology, build circuses, coliseums, zoos and what not. Wonders are out of the question atm, but many of them have good happiness perks. Your cities will not grow while unhappy.