Yeah, again, when I first recommend Writing I for some reason thought this was a Noble game. So TW has merit. Still think Writing first could work fine here simply being a tad more cognizant of the commerce you do have available and more judicious settling. 3 to 4 quick cities is fine, but you can even build those additional settlers and hold them a bit until writing is in...snap..quick Creative Libraries and all is fine.
Regardless, you are learning some good things here and likely expanding far faster than you've ever done before. The semi-iso will present some challenges with trading. Indeed you want to open coastlines for those foreign trade routes. I would use a workboat for that. Sailing is probably a good tech to go for after Pottery...it's not like you can trade for it anyway and those routes will be vital here.
Basically you will be stuck in a no tech trading situation until Optics, except for maybe some specific techs like Monarchy.