Just glancing at your numbers, and a blank 2555 plus Schedule I, it seems to me that your adjusted gross income (assuming the UK income of 14K-ish is excluded) will be $8K from your US self-employment. Your standard deduction is $12K, so your taxable income on line 10 of the 1040 would be $0. But I could easily be wrong as it's been years since I filled out a 2555, and the sol-called tax reform has generated new/different forms.
In any case, you don't get a refund for unused exemption, but neither would you pay any US tax for 2018 if your taxable income is $0. Again, this is off the top of my pointy little head, making assumptions on the info you provided. Someone with more knowledge and better reading ability than I will no doubt step in and help out.