Firstly ditch the fags, they really won't help you or the baby. Secondly tell your dp to get back in his fucking box and shut the hell up ... and whilst he is on his way, make you some dinner and get you some fucking chocolate! How dare he! Grr fuming on your behalf.
I was about 57kg when I got preggers and weigh about 76kg now with another 9 weeks to go. I seriously think that us smaller ladies put on more weight during pregnancy than those who are larger. We need it, to feed the baby, for labour and breast feeding. I have been addicted to chocolate - although now converted to chocolate covered ice cream. I can't help it, but I do try to limit myself to one thing a day. Sometimes that is a small chocolate biscuit, sometimes it is one bar of chocolate (size varies from 35g to 500g
) but it is still one thing per day! Try the same, chocolate is good for you, makes you happy inside.
I've no advice about how to loose weight post birth, but I've heard breast feeding works a treat. If not, it really shouldn't matter, give yourself some time to recover, eat well, look after baby and get some exercise when you can. If you look after yourself you'll get back to where you were.
And seriously, have words with the dp. He should be supporting you and reminding you how amazing your body is growing a tiny person, and how much he loves you even if you think (or even if you actually do) look like a whale!