RedKettle is right, but there are other issues with this map. It's late here, so I'm going to keep this brief (and apologies if I seem brusque or harsh).
First, your streets are too straight. Look at some maps of old towns (Siena, Italy, is top of the list). They have angles, courtyards/piazzas, and curve-like streets. Bascally, they are a mess (there is always reason behind the madness, but I won't go into that now). Your map lacks that chaos.
Second, and this is a major pet peeve of mine, and something which heaps (most?) of city mappers are guilty of: in old cities, buildings DID NOT SIT APART FROM EACH OTHER! They would always share at least one wall, and probably 3 (or 6 or 7 if they weren't rectilinear, which was usually the case). Once again, there is a pattern behind it, but the gist is, streets are the bits between the buildings and not the other way around. If nothing else, streets should represent only a tiny fraction of the urban space (gardens and buildings occupying the majority; yes, gardens were common in old towns, although their purpose was linked more to food production). As I said before, you should take a look at the likes of Siena, Rome, or Venice (those being excellent examples of large cities relatively unchanged in their central districts).
Oh, and one final thing: it was unusual for a medieval or pre-medieval town to have walls within walls. More often, a single wall around the edge of the settlement, often with suburbs appearing beyond it. Fortified walls are expensive to build, and occupy valuable urban space. In most cases, they would only be built if there was a genuine need for them (usually defensive, but equally about collecting taxes/tolls). Just something to consider regarding the wall around your town's inner sanctum.
Good luck. Don't be discouraged.
THW.