did i make a med error?

So here's the thing.

A pt was ordered tazocin 1.7g, we had a 4g vial, which was to be mixed with 16.8mls of WFI and that would give us a concentration of 200mg/ml.

There are two ways of giving tazocin.

1. iv push undiluted over 3-5mins.

2. dilute it to 10-20mg/ml and infuse it for over 30mins.

so once i got the initial amount of 8.5mls (1700mg/200mg), i diluted it with 77.5mls of N/S which gave us a total of 85mls (10mg/ml).

Then I infused it for 1hour. (I was afraid of giving such a large amount in 30mins, and i know i'm supposed to give it over only 30mins).

The pt had IVT running at 82mls/hr, while i was giving the 85mls I put the IVT on hold.

At the end the other RN came and told me i gave the patient too much fluid, just wondering if that's true or not. The other time I watched that RN gave tazocin, and she only diluted 8.5mls with 10mls of n/s and then infused it over 30mins..