Are you describing an empty bar or the bar with 45 pounds of weight on it. Not sure how you can make a bar lighter so you must be talking about the bar + weights. If that is the case you were pressing 90 pounds. Take 30 pounds off and do your fives.
Normally when you see 3x5 that means 3 sets of 5 reps. You need to take weight off so you can do 5 repetitions, and repeat two more times.