NorthernKeys

A lot of IRS can be more of an honor system. Like reporting your interest. They don’t know about it because your bank isn’t reporting to the IRS.  American banks tell the IRS what they paid you and give you the same info on a 1099-INT. If you didn’t report that, the IRS computer would flag you.
 
Yes, certainly you may file together. Your share of the standard deduction will reduce her taxable income. You should be able to pick up the stimulus payments for 2020. You spouse may have gotten hers early. 
 
Another note: I do the FBAR every year but forget it in between, I believe somewhere in that online filing it will ask if the account(s) you are reporting paid you any interest. If so, did you report it on your tax return? And you did and can say Yes.  

Did you receive any interest income? Yes
You carry on and tell how much and from whom whether you have a statement like a 1099 INT or not. That’s an American form. You aren’t required to submit your proof of interest. Just claim it.
 
I have self employment income from a US business that just can’t get it together to issue a me a 1099 wage statement. I enter what he paid me based on my records and carry on claiming the income and paying taxes on it.
 
Where do you presently live? If you have no US income and still live abroad, why are you filing a joint return? If either of you have UK income, you must report it on the US return.

For U.S. broker's, they are required to give you tax statements.  Most are not mailed these days, so you might have to dig online for it.  I just got my taxable interest from Fidelity last week.  Not sure about British brokers. 
 
For the interest, I'm not familiar with Turbo Tax, but it looks like if you continue on from the screenshot you posted, there will be a place to put it in.  Here is a screenshot of my 2019 schedule B.  I don't get a 1099 for Bank of Philippines, but my CPA puts it in.  I have no idea what software he uses but I am sure Turbo Tax has a way.
 

YES, your file FBAR and report the highest balance during 2020, not the current balance. It is not part of the tax return, but Turbo will remind you to submit it. It is an online submission of a report...Bank name,address, account number, and highest balance. It is not taxable money. 
 
Report the interest where you report US interest— Schedule B and then Form 1040 Line 2b for the total of all interest. It is taxable.
 
That’s our favorite. 

Thankfully, I have an outstanding CPA who always handles our taxes and FBAR.
 
The FBAR is not filed with your tax return, and it is not filed with the IRS.
https://bsaefiling.fincen.treas.gov/NoRegFBARFiler.html
 
"
Who Must File the FBAR?
A United States person that has a financial interest in or signature authority over foreign financial accounts must file an FBAR if the aggregate value of the foreign financial accounts exceeds $10,000 at any time during the calendar year. The full line item instructions are located at FBAR Line Item Instructions."