Growth requires a few things. Getting goods into a city is the 1st. Giving people routes to other cities is the 2nd. And to me the most important.
Try this, make a small map. Pick the center most city as your hub city. Connect every other city to that one. Setup a city to city route from the other 6 to it. I design that middle city myself. I will have 4 tram/bus stations there. 1 NW 1 NE 1 SW 1 SE. Then design a bus route in each city to move the people to your stations. This gives everyone access to each city.
Then, I worry about freight. I find the most central industry on the map. That one factory will supply all 7 cities for many decades.
If you set it up right, that middle city will grow like crazy. I have went from 117 to over 500 in less then 10 years.
Later if you grow right, you will need to add another factory or 2 to keep up with demand.
Cause’s for factory not growing is simple to trace. Turn on the freight overlay, it shows where the freight is moving. If you see freight leaving your truck stations and going to town or industry by themselves, you do not have enough capacity. Keep an eye on auto delivery, it can ruin your chance to upgrade.
Always check what your cities need for carrgo, setup right they should all grow quite fast.
Just an FYI, I have no issue’s taking out a 10 mil loan at start of the game. You can easily run med roads from each city your hub city and setup basic people movers. You will be rolling in cash to be quite honest. I average paying off the loan by 1857.
I also destroy almost every road the AI makes since it does such poor job of it. Some people claim it is cheating, but I paid for the game and cannot stand ugly roads.