you'll have 2 floodplain farms, two grass farms and two cottagefarms. 8 food surplus from those will allow you to work 8 flat plains/grass hills while still growing. add the dragonbones and you get 6 + 8 + 1 = 15 tiles workable without issues.
how big is that city gonna get anyway since you want horizontal growth, not vertical?
also, you're definitely going to be using agrarianism before you get conquest, so that's another 4 food for fast growth in the critical early game. hammers from plains/hills are just as good as food in conquest, so I don't think you need much more.
farmed non-wet wheat is 3F1H hammer anyway which is less than the northern floodplain farm you would lose, and you'd also be further from the river in a more hilly spot, so less food and less commerce, both vital early game. a couple riverside flat plains cottages would be great to have, as you'll need commerce for unit upgrades.