You have made a scale floor plan. You should go ahead and draw in any windows and/or exterior doors. You can locate them accurately by measuring from a corner to a windows edge, then measure how wide the window is. Next measure from the edge of that window to the edge of the next window and so on.

Overall sofa size can be from 70" to 96" long and from 30" to 40" deep. Look for this information on any seating that interests you. On a separate piece of quadrille paper, draw out the exterior dimensions of sofas and tables to the same scale as your floor plan. Label each piece and cut it out. Label similar pieces by different manufacturers so they aren't confused with other collections. Now you can lay the furniture pieces on your floor plan and move them around until you are satisfied.

As an aside, cushion sizes are usually 18" or 20" square but can be up to 24". Sofas with deep seats are more comfortable for tall people, but shorter people will require a throw pillow to feel comfortable. And the height from floor to the top of the seat is also important to comfort based on your height. This height can range from 15" to 20" with 17" or 18" being most common. There is no substitution for trying out furniture for comfort before you buy it.

You are interested in a sectional which is typically a sofa length and a loveseat length joined by a square corner piece. This Houzz ARTICLE explains the basics. You want to put the TV on the 12' wall, so placing the longer sofa length on the right 16' wall with the shorter length facing the TV would provide more access space into the room. Accent chairs on the left wall can be turned for TV viewing or conversation. However, your room is wide enough to place the longer length across the space. I personally find the corner of a sectional to be uncomfortable—one's knees are scrunched together and there is insufficient back support. Rounded corner sectionals don't have this problem but do add to the overall footprint of the sectional.

Darken the plan. Bold the llines and dimensions. Put the windows and entry points in Nobody can read it.

Better??

It's not ideal...............But neither is the entry sp0t . For what you WANT? ( seeing tv from dining and kitchen ) Pay attention to the sectional inches.

Accent chairs at no more than 30 x 30 .Don't forget lighting ( standing and table top.Rug dooted line is 9 x 12

If you have stool at the kitchen ? The small Shallow console and lam go. ....away.

Those are MAXIMUM sectional inches.