Had to get tested for work

PCR just came back negative (no active infection)

Antibody test on Thursday last week had IgG (Neg) and IgM (Pos)....

My interpretation is that I recently had it (no symptoms) but it's already gone from my system...

Is there a chart for the results? Could find one online on a quick search but I am sure they exist.

The PCR is a false negative or the IgM is a false positive. No test is 100%. The nasal swabs can be negative because of poor technique-it happens all the time, or very low viral load. I'd make the assumption you have it until you prove you don't (with a repeat, properly done PCR).
Edit: you could be in a very small window where you're convalescing but your IgG levels haven't shown yet. Either way, it merits a PCR if for no reason than to determine whether you're contagious.

"IgM refers to those antibodies that are produced immediately after an exposure to the disease, while IgG refers to a later response. IgG generally confers immunity to a patient so far as that particular disease is concerned."

But IgM takes a few days to show with COVID-19, so one can still be infected and have negative antibodies. Conversely, people can shed "dead" virus and have positive PCR tests for a while when they aren't ill and probably aren't contagious.

That's cool, I just needed to be sure what each stood for exactly. Just definitions of the terms.

You are either early in infection (day 5-7) with a false negative PCR or you just cleared infection and IgG should kick up in the next week (day 7-14)

Understanding antibody testing
Above is a link for an article written for orthopedic surgeons (you can tell because it says so in the abstract, and there are lots of pictures). If you look down to the algorithm for how to treat patients with your test results, you'll see their recommendations for antibody testing when IgM is positive and IgG is negative:


IgM is Positive and IgG is Negative

This test result indicates that the immune system is actively producing antibodies to a recent infection (Fig. 3 ). The subject should immediately isolate from healthy individuals and seek further medical advice if symptoms develop. This subject can likely spread disease to others, even when asymptomatic. The subject may remain symptom free, experience minor symptoms, or worsening symptoms as the disease course progresses. The subject should be vigilant and seek care appropriate to the symptoms they experience. After at least 14 to 21 days, the subject should consider repeat testing to confirm their IgG antibody status has become positive and they are outside the expected window to shed virus before returning to normal activities. If more rapid return to community activities is warranted, for example, for critical industry workers, a molecular test should be performed to assess viral shedding status.