You either need more power [1] or a higher nicotine strength [2] - or both. Once you are nearly there, experiment with the percentage of PG vs VG in your liquid refills.
Once you've got those sorted out you should be OK. However a small number of people need something else from tobacco as well as nicotine. The best way for you to get that would be Snus [3]. Some of us get it from TE (tobacco extract) added to our
e-liquid, but in your case Snus would probably be easier to sort out.
[1] There is a power scale for hardware, it goes something like this:
Power Factor 0.75: main street e-cigs, high resistance atomizer models such as the 901, penstyles.
Power Factor 1: a stock 510 model
Power Factor 2: a 510 large-format model with a low-resistance atty, ex: eGo, Tornado 510 LR
Power Factor 3: a 5 volt mod with a stock 510 atty, or a 6 volt (or higher) mod with an HR atty
Power Factor 3.5: a 6v or higher mod
Each step up the scale is a doubling in power - PF2 is double the power of PF1, meaning the effect that you feel in terms of vapor and TH (throat hit). So basically you will get more hit if you change to a good model like the 510, then double that if you go to an LR atomizer, and three times the hit with a 5 volt mod. Some people need a big hit, to get off the coffin nails, they might need less hit later on. I needed a 5 volt mod along with fiercely strong
e-liquid, nothing else worked for me. Now I use a Tornado LR most of the time, and a mild liquid (but still with high nic much of the day). People's taste varies widely, and any one person's taste can vary over time.
[2] People need different amounts of nicotine, and it has no relation to how much they smoked. The nic strength of e-liquids goes like this:
Low: 6mg (0.6%)
Low-plus: 12mg (1.2%)
Medium: 18mg (1.8%) [this is the average strength
e-liquid]
Medium-high: 24mg (2.4%)
Medium-high-plus: 30mg (3%)
High: 36mg (3.6%)
Super-high: 48mg (4.8%) [only used in difficult cases, for those with high nicotine tolerance]
You might need a high strength at first. If possible reduce to an average strength, when you can.
[3] If even the high strength doesn't do it for you, you most likely need Snus as well, as you need something else in addition to nicotine. Nobody really knows what this is, there are dozens of theories - but it's in Snus and correctly-made TE.
Snus is a Swedish invention, oral tobacco in small pouches, prepared in a way that results in a convenient and safe way to use this type of tobacco. It's been used for a long time and is proven safe (Swedish men have the lowest cancer rate in Europe due to the fact many use Snus instead of smoking; however it's not popular with women there, so their cancer rate is about the same as the rest of the region).