What about a bigger size?
Money is my biggest concern though. I'm not expecting to get much bigger anyway, but the slightest change will make a difference with chinos especially. Same goes for leather jackets. For example I can't bend my arms properly to smoke when I'm wearing it.

Now as you've seen, I'm a really not big at all. Maybe I should take that as a sign to stop smoking.
Clearly he's concerned about his slim fit chinos like any proper ladies man..
- - - Updated - - -
Don't worry unless you are on them roids it'll take ages before you get "big". Just make sure your caloric surplus is moderate.
I've gone from 72 kg to 78 kg and I still fit them slim fit, but I've got hella long legs and not a stumpy midget like build. But as I remember so do you?
You just explained myself there, except that I went from 70kg to 78kg in 4 months and am about 6'1 tall. My legs are huge.
My problem has got more to do with money than clothing or style though and legs are the least of my worries.
- - - Updated - - -
Dusan
