Why when I had 13,886 in honest deductions, turbo tax would only let me use the 13,600 ?

There are limits on some itemized deductions starting in 2018. For example, if you have an outstanding mortgage balance on your home or other non-business use property, you can only deduct the interest on the first $750K of the outstanding mortgage. (If the outstanding balance was more than 750K on Dec 31 of the tax year, then this limit kicks in for you.)  Also, you're limited to a maximum of $10K on your SALT deductions (State And Local Taxes).

They also took away unreimbursed employee business expenses as well as most of the other miscellaneous itemized deductions...so if any of those figured into your total of 13886, you may not have as much as you think.