I really do know how you feel, you are not alone.
First of all, you are not a pathetic loser, and you are NOT going mad.
Secondly, bloody well done for cutting down as much as you have done.
Thirdly, only you can make the decision to give up, nobody can make you, nobody can force you into making it, it has to come from inside you. If you do get criticised for smoking, try to ignore it, they don't know, they don't understand and most of all, they are not in your shoes.
A few things I will share with you:
I didn't manage to give up entirely with any of my pregnancies but I have now given up and speak as a smoker who doesn't smoke at the moment (tis a bit like being an alcoholic I think) so I really do know what I am talking about...
People will look at you and stare at your bump if you are having a cigarette whilst obviously pregnant. People will think that it is acceptable for them to come over and tell you all the harm you are doing to your baby. You will feel guilty every time you have a cigarette, no matter what you feel about the safety of smoking whilst pregnant. You will occasionally get tuts from HCPs when they ask how the smoking is going.
On the other side of the coin: Since I gave up, my hair is healthier, my teeth are white again, I can push a pushchair up a hill without stopping half way up, my freshly decorated walls are going to stay white and most of all, when people offer me a cigarette I can say "no thanks, I don't" which is fantabuloso!
A final note... all three of my babies were quite small.
Good luck with whatever you decide to do. IF you do decide that giving up smoking is right for you, feel free to cat me, or hunt me down on here and I can give you loads of hints/support... whatever you need.
xx