Infusion error and I feel terrible!!

So, I have been a nurse for almost 20 years. I know no matter how careful we are as nurses we all make mistakes. For the past 3 days I have been reading many other's stories about making a mistake in their practice. I have always been one who throws myself under the bus when I know I have made an error. Not to say that I make mistakes often, but in past instances I have been able to reflect on the mistake, forgive myself and move on. But 3 days ago I made a poor judgement call that although did not result in patient harm, I am having a hard time getting over because I know it could have had a bad outcome.

The patient was ordered for both a 1 liter bolus of NS and a bag of IV Sodium Phos for a phos level of 1.2 (thank god it wasn't kphos!). I went to the patient's room, scanned both bags, scanned the patient's ID band and then spiked both bags. The patient's access was a double lumen PICC with 1 line dedicated to TPN. (Here's where I should have stooped what I was doing and gotten a third IV pump). Normally this is what I would have done, but for some reason I decided instead of getting another pump, I would run the bolus as a primary infusion and the Soda Phos as a secondary. But because the soda phos would need to run over 4 hours, I decided to run the bolus first and return in 30 minutes to run the soda phos. (It also would have made sense to run the soda phos as a primary and the saline as a secondary). But nonetheless I returned 30 minutes after initiating the bolus to find that none of the saline had infused and the entire bag of soda phos had gone in. My heart sank and after looking at the patient's monitor and the patient to make sure she was still alive, I ran out to the nurse station. I immediately talked to the resident about what had happened. He replied, we'll check labs in 2 hours to make sure everything stays ok. The attending MD came to the floor a short time later and I also let her know my error, she too did not seem overly concerned. She said "Its ok". I called the pharmacy to find out if there was anything else I should be watching for. Her reply was "If anything was going to happen, it already would have". I checked my labs at noon, the Phos level came up only to 2.4, the calcium level was normal and the BUN / Creat was low, but the patient had just received the bolus. I filled out an electronic incident report and when I checked the patient's labs at noon I informed her that I was checking the labs since the IV went in faster than it should have. I emailed the unit manager with a detailed outline of what had happened and I cc'd my own manager as well. The response I received from the unit manager was "Thank you for the details". I still haven't heard anything back from my own manager and because I'm off until the weekend, haven't had an opportunity to see her face to face.

I'm not sure if I'm overreacting to this incident, after all the patient remained absolutely stable, or if I might walk into work this weekend and be fired or worse, be reported to the board of nursing because this seems like a really big deal! If only I hadn't spiked the bag of soda phos, or thought to run the bolus as a secondary and the soda phos as a primary infusion.

I've been searching for answers since this happened and I did come across an email from last year, that said the pumps we use did have a prior issue with over and under infusing, but that issue was resolved by biomed. But, ultimately it was my mistake to leave the bag of soda phos hanging.