I get the impression that you are selling without professional representation, is that correct?
A couple of things for you to think about:
The rule of thumb we use is 10-12 showings or one offer in the first two weeks a listing is on the market (assuming the property is listed with a Realtor). If you don't have enough showings you won't be able to get an offer.
Homes sold without professional representation sell for about 16% less than those sold by Realtors. Although you might be able to sell on your own, which would be great, know that 85% of owners eventually list with a Realtor. My suggestion is to interview three Realtors, then if you do need to list, you'll already have one ready to go to work for you.
When you bought your home you probably used a Realtor. Why? Because for buyers we work for "free". It would not surprise you that when a buyer first sees the home they purchase, they see it with a Realtor 90% of the time. So when you try to sell without professional representation, you are basically working with 10% of the market. So is it any wonder that homes sold "direct" sell for less? Makes complete sense.
The reason I make these points is that although having a diagram my be helpful, I would not want to give you the impression that your home will sell if you have a diagram. What you need are more showings in order to get an offer, and without massive exposure that a Realtor can provide having a diagram may or may not make any difference.
On a technical note, you are legally liable for what you say and do to market your property. So if you decide to make your own diagram, it had better be accurate. We normally hire a professional company to provide diagrams so if there are errors, that company is legally liable.