First off, try not to compare yourself to other pregnant women. Just like every baby is different so is every pregnancy. What's normal for one woman won't be what's normal for you. We all start out looking and weighing differently before we get pregnant, so we're gonna put on the pounds differently too.
I'm 26 weeks now, and as of my 24 week appt I have gained 18 lbs. I've developed some bad eating habits thanks to cravings. I gained a lot of weight with DS too, I gained about 45lbs total with him, but it all came off after he was born.