By how much am I underpaid?

Short of sharing my CV and current salary with everyone and getting opinions, how can I figure out of I'm being overpaid, or more likely, underpaid in my current position? I suppose it is a question of underpaid but by how much.

I put out the first number in recent negotiations against my better judgement. I was recently laid off and did not stick to what I knew I should have done by not putting out the first number. The firm asked me for my "take out" number and I quoted what I thought was pretty high. They wound up exceeding my figure by 7k which I thought was a nice gesture but not a good sign as to if my anchor was high enough. Now I'm kicking myself by not putting out a much higher initial figure. However, I do know by talking to a 3rd party recruiter that I got the offer over a candidate they were working with, so maybe I'd be upset the other way if I put out too high of a figure and didn't get the job. I know that "being affordable" is a thing and that if a candidate is too expensive a company might go with their second but less expensive option.

I'll have a chance to discuss salary in 6 months but unless I really crush it I doubt there is room for movement so soon after starting.

In any case, if anyone has some good insight into how to figure out what I could be making I'd appreciate it. As an FYI I am working in DevOps / SRE for a financial company.