I made my first bottle of e-liquid 2 days ago. It is a Juicy Fruit flavour and it turned out well but it is a bit harsh, has a stronger throat hit than I am used to. My nicotine dosage is always 18 mg.
If it’s harshness/TH your talking about I would start with sampling each part of the base separately. Start with just the VG (No flavor) then the PG (No flavoring) then mix your base at the mg that you vape (no flavoring). If any of these components are harsh then replace it with a different brand. It’s all process of elimination. I use essential depot PG and VG myself and don’t find any issues with it. I found some vendors/suppliers nicotine to be harsh. Could make a mix w/o nic and see TH vanishes.
“Since PG is partly responsible for throat hit, should I maybe increase the VG to 80%?” I would change to 80 only if I was sure the PG was causing the problem.
If base is good add one flavor at a time to the base and again keep doing that (Sample each flavor with clean base) and eliminate the offending flavor.
If you get harshness with a new clean brand of PG and VG or both when sampling separately I would look towards hardware (Over voltage, running to hot, burnt dirty coils etc…)
My guess is it’s the brand of nic your using.
“Should I try doubling the Sweetener” Yes, could even go to 3% YMMV.
Steep: 1-2 weeks would smooth the mix.