Is it worth being grumpy and fat for? Well smoking artificially increases your metabolism and suppresses your appetite, but 1 or 2 cigarettes a day won't be having a major effect on either. Grumpy, well it depends. Using the E-Cig or nicotine patches would keep the withdrawal symptoms away. But at some point you will need to give up nicotine completely, slowly lowering the dose and going cold turkey is the best approach. You might gain a bit of weight, and feel grumpy, but those all temporary setbacks to gain long term freedom.
1 or 2 cigarettes a day is no worse for you as a day spent in Central London inhaling all the fumes. I'd say aim to quit, and move onto the E-Cig completely. But do it in your own time. You have cut down by quite a bit and you've down well. Best of luck mate.