I've put on weight too but I probably would have anyway over Christmas with all that Christmas food. Normally I'd put myself on a diet after New Year's but at the moment I'm either hungry or sick and I'm just grazing the whole day. Today I bought watermelon, cherries, strawberries, grapes, plums and bananas and I'm working my way through that lot! And I'm keeping up a gentle walk in the mornings and evenings with my old dog, which we both enjoy
So, yes, I think a slight weight gain is normal unless you're so violently sick that you can't keep anything down.
Congratulations again, Pindle, and wishing you a happy and healthy pregnancy!