The most simple answer is that you delete this model and start a new one with more geometry from the scratch. As hard it might sounds, sometimes it's the best solution if you want to do a proper model. It happened to me many times. I started with 8-points cylinder and it all went down the drain when I started adding details. You don't have to be "cheap" with geometry. In start it might seem too much but in the end you don't have to use large subdiv number. With good start geometry, you can end up with only subdiv1 which will give you same result as subdiv3 but without pinching problems.
Have you tried to solve up-right geometry as you did on the bottom-left (three points merged to one and continued to edge that goes up)? Maybe on this bottom-left is also some shading but maybe it's not so important (and visible) for final product.
Third solution is to continue theese edges over the wall and then eyeball the geometry to get the best result. [WARNING: This is very intimidating process for persons with OCD (which we all have)].