How serious is this detention?

So I have got a job in a city a year ago and I was on asylum pending and f1 status at that time.
The job was in a city next to the Canada border. I had to drive 30 -40 minutes to work and two weeks after I have started the job, one morning I made a mistake and instead of turning to the road to my work I turned 500 feet early and turn to Canada border( they are really the same and easy to mix up).

The moment I turned I realized I made a mistake so I told the officer I want to turn back and go to work.
He told me if I am a citizen or green card holder and I said no.
He said I have to come inside and I parked my car and went inside.
They took my fingerprints and my picture. asked about my asylum case, my opt, my job.
They let me go after an hour and a half and told me that almost 100 people weekly make this mistake and turn to this road instead of the next one.
I went to work and explained to my boss and she even told me she made the same mistake at the start of her job in this new building.
Anyway, I filled for a green card by myself on February and for the question have you ever been detained I answered no because I didn't know that I actually was detained.
I mean no one put anything around my hand and they were kind of normal with me.
But then a couple of weeks ago when my interview letter came I contacted a lawyer and she told me I had to answer yes to this question.
We draft a letter about the event and I want to bring it by myself to interview, and also I bring my lawyer to the interview as well.

But I am a little worried. I answered no to the question have you ever been cited or detained, and I didn't know I was detained and also I had two traffic tickets and I didn't know I should have mentioned that either.

for one of my traffic ticket, the courthouse waived the fee and didn't take points from my driver license but I don't have any document to prove it.
for the second one, I have a bank statement that I paid in full for my other ticket.

I am planning to give the explanation letter about my detention and talk about my traffic tickets in my interview day.
However, my lawyer recommends to not bring up the traffic tickets unless they ask for it. but she wants me to talk about my detention for sure that I will.

How big of a deal are these things?

Should I be worry?