Nice little shack!

It looks as if you may have a corner-join issue (SW corner). That could be because you started drawing the walls at the corner. If so, you might instead try starting partway along one of the flat sides, as if you start at a corner and then add a break in the wall - such as for the door - you can end up with this odd-looking effect otherwise.

And maybe add a window?

Looking at the symbol and terrain use here, I think these could be used to create an illusory city too, or a literal ghost town, perhaps with some additional colour overlay effects, and perhaps some transparency about the symbols (less sure about the latter point, however). Or indeed a city of glass.

Excellent! And now without the canvas roof? 😁 And then with the anti-aircraft guns mounted on the rear. And...

You know Forum folks - we ALWAYS want more symbols!

And now released into the wild! Wrap up warm and go exploring folks!⛷️❄️☃️

While the size may seem wrong, by a strict comparison with some medieval European structures, this isn't for medieval Europe, it's for fantasy D&D, and is close to the scale size for this specific tavern as shown on Mike Schley's map of Saltmarsh in the Ghosts of Saltmarsh scenario book (Wizards of the Coast, 2019), assuming five-foot grid squares here. The appearance isn't quite the same as on that map, but this is an adaptation after all, and although there are a number of designs for the Wicker Goat Tavern online, I don't think there's an official D&D version, so some leeway is to be expected.

In the original adventure (The Sinister Secret of Saltmarsh, TSR's Module U1, from 1981), you were expected to create your own version of the town from scratch - there are a few guidelines for key points, such as Point 4: "Decide where the characters could stay when resting in the town between adventures (the best inn? the only inn?); draw up a tariff (list of expenditures) for their accommodation and food." But that's as close as we got to a description for the inn/tavern, which didn't even get a name back then!

That's not to say such points should just be ignored necessarily, and the heating and access points are useful considerations. However, if the final tavern is meant to fit to the size of the official Saltmarsh map, this is close enough to work for that.