Well, you've not said whether the 4ml of nicotine is in PG or VG (or both), so you are
vaping unflavored somewhere between 60:40 and 73:27 PG:VG.
I am somewhat similar -- I started making unflavored when I first started DIY a month after starting
vaping. Back then I used 80:20 PG:VG, but these days I use 50:50. I do often use lightly flavored juice as well (you know, like a whole drop of TFA Menthol and/or FA Vanilla Tahiti in a 30ml bottle). I also make some stronger cigar flavored liquids that I directly drip on the coils of and RDA on a squonker filled with unflavored and let the flavor fade as I vape and squonk.
Nevertheless, I do suggest all DIY
eliquid makers (especially beginners) make and try some unflavored at their preferred nic level -- it is clean and easy on coils, does have its own flavor, and, like in cooking, you should get to know your primary ingredients.
edit: By the way -- Welcome to ECF, relax and pull up a stool to the vapebar!