Now we have something understandable.
This is your recipe plugged into my e-liquid calculator:
View attachment 748927
(Note: you can click on the image to see a larger, easier-to-read, version.)
Now we can better address your original post (OP).
From reading your attached nic link; it appears you have standard freebase nicotine (not Nicotine Salts). So, there should be no extra "smoothing" in that regard.
4.32mg/mL nicotine is
not going to have anywhere even remotely close to the same TH the undiluted 72mg/mL has. If you want to increase TH without increasing nic content; you could try raising the PG level, and lowering the VG by the same amount.
I am skeptical that you are using TFA-Chocolate (TFA = The Flavor Apprentice). The link you shared is showing the flavors labeled as "MFL" and "My Fresh Lab made in UK." I don't know what that is; but it is
not TFA.
I point this out, and make the distinction; because a flavor concentrate from one manufacturer, may not taste the same ore be used at the same strength, as a concentrate from a different manufacturer... even if they have the same name ("Chocolate" in this case).
I know nothing about MFL; so I can't offer any advice. I saw (in another forum) that
@ceeceeisme ha used some MFL. Perhaps she might be willing to share her thoughts?
Eyeball measuring, as I am sure you know, is not ideal for DIY. This could be further reason why you are not getting the TH you were wanting. You
intended to add 3mL of nic; but
maybe you only got 2mL or even 1mL of nic. That would certainly reduce TH too.
I am also seeing, that you mentioned using
8mL of nic in your original post, but when you finally shared your complete recipe it lists using only
3mL. That can also make a big difference in TH. 8mL whoud provide 11.52mg/mL; while the 3mL is only giving 4.32mg/mL.
Using more precise methods, like syringes, a scale, or graduated cylinders, will provide you much better, more repeatable results.