Yes tt's normal. I only put on abt 3kg frm my first appt at 8 weeks till end of 2nd trimester despite eating significantly more in 2nd tri. But frm 30th wk to 35th wk now, I put on close to 4kg with even much less food (easily full). Baby also growing rapidly now, frm just being 1 week ahead of his gestational week, now he's as big as a 38th week baby (actual 35th wk).
So don't worry abt not gaining weight as long u consume enough nutrition (food and/or supplements), baby will be fine!