Maybe you need to give yourself a scheduled break. Like “for the next 20 minutes I will not think aboutthe project. Then I will work on it for 5 minutes then take a 5 minute break.”
I think my only problem is negative symptoms as I had no real concentration issues off meds or on Abilify when my negative symptoms were less. But before sz my concentration was a lot better, even my teachers told me that I have super concentration.