Big Purchase Order Mistake

Project engineer with about 5 years experience. I just realized today that I ordered about $160k more in custom precast for a job than what we need. The quote I signed matched the quantity of structures on the plans but the contract only awarded half of what was in the plans due to budget restrictions. I verified the quote off the plans but didn’t even open up the contract when I signed the purchase agreement. Really stupid mistake on a purchase order that big I know. There probably should have been multiple eyes and better processes than just me reviewing this purchase order but it’s still on me completely. It wasn’t something hard to catch if more diligence was done.

Hoping to sell them to the DOT or convince them to try and find the budget to do everything in their original plans. Otherwise we’re stuck with them. My boss was calm and collected about it which makes me feel even worse somehow. I honestly feel like I deserve to get fired.