How does nicotine negatively impact concentration and how to quit with ongoing projects

Hello, long story short do a can of 6mg zyns a day. Got down to 3mg while sick a few weeks ago and then quit entirely for 6 days but dumbass me had to go back to them even though I barely had withdrawal other than fatigue. Since I wasted that chance, now I’m wondering how nicotine really affects cognitive performance as I can’t tell if it helps me or doesn’t. Sometimes it helps me lock in crazy and then other times i take one and get too anxious and stare at my screen doing nothing. I also can’t tell if it’s affecting my motivation, some days I feel highly motivated and others I feel like I don’t want to do anything but stare at a wall.

I also ask this because I am a programmer and I’m working on two big passion projects right now and I really don’t want to lose my grasp on them since I’m somewhat on a roll. But recently since my nicotine intake has increased back a lot, I havnt been making much progress. The last thing I wanna do is lose all motivation or concentration ability for them so putting health aside I really want to know what cognitively will happen if I do quit or if I should be more careful and taper my dose. I will say tapering to 3mg does help me a lot but even that made me a bit lagging on my projects.