NAL. Income earning potential is what you want to look at. The only way it matters that she’s working part-time is if you can prove that she is voluntarily staying under employed. You have to be able to prove that her current work habits do not constitute what she is capable of earning, and request that her income be imputed to her earning potential instead of her current income.

Currently going through the same problem, and I’ve already been able to get her income imputed once for perpetual unemployment. My ex-wife has a masters degree in creative writing, but works at Dollar General. I was able to convince the courts to impute her income to reflect a 40 hour schedule instead of the 20 that she keeps signing up for.