How to ensure I'm not over paying tax on my UK rental income?

Hello, 

I am a 'resident alien' with a rental property in the UK that I receive standard monthly income on which is declare to UK tax authorities. 

I have listed this property and income on my return (Sch E) and am in a loop trying to add foreign accrued taxes (it won't let me add them in the Foreign Tax Credit or Foreign Income Exclusions). My return says I need to pay $2,532 which doesn't seem right to me, please can some try and help me understand what's going on? I've been online with two different advisors and they don't understand how to help and I've received conflicting advice.

Here are some of my details in case pertinent to the advice:

I'm filing with my spouse

Our US income is $285,000

Foreign rental after expenses $20,000

Taxes paid already $52,000

Taxes 'due': $53,500

Is that right? Has turbo tax done some sort of calculation but not explained it to me? It won't allow me to add a 1116.

Thank you for any help!