Quite often, cities such as this develop to a point of having a large outer wall, but before this there is a castle with it's own walls and peasants outside of the castle, who, in the time of danger, would retreat to the inside of the castle. This means that the castle is always growing with the town, and should be (if you include the courtyard, keep and such) that the castle be much larger than shown.

Eventually, another wall would likely be developed inside the city to hold the nobles and richer folk, a wall which would likely be paid for by taxes and could only be afforded by these people stated above. This would be like an add on to the castle, which it would eventually mold into to become a part of, making the castle even larger and stronger. This proccess would repeat over and over until rings of walls would develop outside the center of the city, but growing smaller and thinner (walls take a massive amount of money to build, especially in that day and age and require a large population of taxpayers to create) which would make the whole city appear like an onion.

In other words, you can definitely have an outer wall of the city, but it will not encase the whole city because many people will have farmland outside the city or simply live outside for cheaper cause (it is undoubtedly more expensive than the interior of the city) and it is likely you will have a massive castle inside the city that people can retreat to in times of danger that would provide the majority of defense, which would be hard to do and, though useful, it is extremely expensive to create the complex network of walls you have inside the city. I mean no offense, but your castle is unfortunately far too small to adequately defend a city that large with an outer wall. At this point the outer and inner walls would be pointless without troops to defend them and large developments of towers and a large castle and keep to retreat to. On another note, you also have the option (if you so choose) to add your church to the castle, as most castles had churches and temples and cathedrals inside of them, not only because it widened the castle and protected them, but often times because soldiers would rarely harm people inside the church, let alone priests.

Another option you may have, and this is simply a suggestion, is that you may not even need an outer wall (or at least a large one) if the people of the city siphoned off the river water to create a makeshift moat that would not only protect them but also provide water for any farms or gardens, assuming they have the knowledge and (rather simple) technology to do so. It would also allow you to build a wall not out of normal materials, but out of a cheaper fencing material; the earth itself, which you would only have to pile up from digging the trench inwhich you have your makeshift moat (probably giving a large about of clay at your disposal if it is so close to a river)

I say all this, although this is your map and your decision on how it came into creation. You simply need to know in advance how your city developed from the small settlement it most likely used to be, and this should influence the development of walls (most walls never started out as walls, but as trenches, rivers, buildings, roads, etc.)