I really hate being negative.
If I remember correctly, this is HO in a 12x12 room. Need to know how the door location corresponds to the aisles. Also, the location of any other doors or windows need to be known.
I strongly suggest drawing the space to scale, with door and window accesses marked, on either graph paper, or on the computer using one of the track planning programs. Then attempt to draw your layout with your selected minimum radius. I think you are going to find that the plan won't even come close to fitting in that space in HO.
In the current drawing - assuming it is roughly to scale - the minium radius curve is well under 18 inches. I cannot see wanting to limit your equipment selection that much to use this plan. Your minimum radius is going to be determined by the equipment you want to use, and how good you want it to look on the curves.
The aisle at the upper right appears too narrow to use.
The reversing loop at the lower left - if built with an 18 inch minimum radius - will have the back track approximately 44 inches from the benchwork edge. This is too far to reach for construction, maintenance and re-railing unless you have access at the end or behind, or provide an access hatch in the center of the loop.
Bottom line: you seem to have settled on a track plan without deciding what is you are trying to achieve. I personally like the track plan, but don't believe it can be made to fit in your space without simplifying it to the point where it loses its character. But I don't know what you are trying to accomplish; I don't understand your vision for YOUR model railroad.
There are a bunch of questions you need to answer before you can select or design a plan that will be satisfying in the long term. John Armstrong had what he called "givens and druthers". Others might call it planning assumptions. Bascially, you need to understand what your priorities are for your layout and what the constraints are.
What is the exact dimensions of the space available, and what are the access constraints?
How big a layout will your time, money, and space support? Complexity is appropriately measured in the number of turnouts a layout has. How many turnouts do you have time to install and maintain, money to buy, etc.? Did you include time and cost to wire, install switch machines, build and install control panels, etc.?
What era and region are you modeling (if any)? What type of equipment do you intend to acquire or have? What is a suitable minimum curve radius for that equipment?
What kind of operation do you prefer? Switching or watching them roll? Do you intend to do dispatching and car forwarding? What operating scheme will you use? How many people will normally be operating the layout?
Are access hatches and duck-unders acceptable? Must the layout be movable? How much time are you willing to spend in construction before the layout is operable? How long do you intend to have the same space available?
Think about these issues, then try to draw a plan to scale in the space available. Post it for comment along with your druthers and givens, and we can better help you achieve your dream.
yours in planning