Land Purchase and Sale Cost Basis Question

I bought vacant land in 2014 and sold it in 2018.  After reading IRS pub 551, I'm still not confident how to document purchase price and sales price.  The most understandable explanation  that I found is here. https://budgeting.thenest.com/tax-basis-selling-expenses-land-30130.html  Can someone confirm that the article explains this properly?  If so, I will need to amend my 2018 filing to in order to subtract the settlement fees from the sale price in order to lower my tax bill. In other words, I may have paid  significantly more taxes than necessary.   Any help appreciated. Thanks.