People generally drive more than 60 miles per hour on highway. Even assuming you were driving at 40 miles per hours (minimum legal speed genearlly), 1 minute means 1,066 meters.
Why do you think you had your left turn signal on for 1-2 minutes? It cannot any further from the facts because for you to have had your signal on for 1 minute, to cover 100 meters, you would have been driving at 6,000 meters per hour, i.e., 3.75 miles per hour.
You did not check your blind spot. 100 your fault.
