I'll start with the basic consequences based on your excellent information.
The payout amounts of your UK State Pension and your UK company pension will be unaffected by WEP. Your US SSA benefit will take a substantial hit.
First, you will need to determine when you will reach your ELY (Eligibility Year). That is normally when you reach age 62. The following chart at the bottom of the linked page determines the
maximum amount your SS benefit can be reduced.
https://www.ssa.gov/planners/retire/wep-chart.htmlIf you wish to go into details, we can, but it is not a straightforward explanation.
If, for example, 2018 were your ELY (and
it won't be), the
Max WEP foreign pension income occurring for those with less than 20 years of substantial earnings is $895/month (at present rates, you're well over this), calculated at the exchange rate on the day the benefit is approved. Any amount of foreign pensions will reduce your SS benefit - IF you have less than 30 years of substantial earnings. $895 is the
Maximum amount of foreign pension income that can be taken into account for those with a 2018 ELY. WEP has a guarantee - you are only dinged at a maximum of 50% of your total foreign pension income OR, 50% of the
Max WEP figure for your ELY (for 2018 - $895). So,....if your ELY is 2018, the
Max WEP amount is $447.50/month (50% of $895).
Calculate your potential SS benefit/month and subtract $447.50.
A very good calculator, which includes WEP considerations, can be found at:
https://www.ssa.gov/planners/retire/anyPiaWepjs04.htmlEDIT TO ADD:
You are 57 now, so you will reach 62 in 5 years time. IF, at that time, you had 23 years of SUBSTANTIAL EARNINGS, the Max WEP amount per month deducted from your SS benefit would be $313.30 (according to the chart linked above for someone with a 2018 ELY - your ELY will be roughly 2023). Use the WEP calculator linked above - it gives a fairly accurate
estimated WEP result for your projected SS benefit.