Oh, weight gain with pregnancy. It's a difficult subject. Yes, you do need to acquire weight. But not too much, not too fast, and God forbid you put any of it in your ass instead of that adorable little "I've eaten a watermelon or maybe just ate a big sandwich" all-in-front baby bump shape that strangely enough society has come to idealise.
All things considered, I am much more concerned about how you feel about your weight gain than I am about it. The true problems in this condition are not the weight; they are nightmares, sobbing, and avoiding social situations. Speaking in terms of your body "failing" you during an otherwise healthy pregnancy is really, extremely concerning.
And yet, despite following essentially the same diets and exercise regimens, some women just put on more weight than others. It can be inherited (like how much weight your mother put on), or it might just be related to your body type and pre-pregnancy weight. The advice for weight growth is also absolutely everywhere. Even your worst-case estimate of 33 pounds at 40 weeks is not particularly startling. Pregnant women in a healthy weight range might anticipate gaining 25 to 35 pounds. Furthermore, achieving the low end of that range does not automatically make you "better" or qualify you to receive the title of Most Virtuous Pregnancy Eater.
What I want you to do is as follows. HIDE the scale. Put an end to self-weighing at home. Your prenatal appointment will be the next time you step on the scale, at which point you can have a rational, knowledgeable conversation with your OB regarding your weight and daily caloric consumption. Preeclampsia can be diagnosed by rapid weight gain (like three pounds in a single week) in the second and third trimesters, but an increase of 11 pounds over the course of 15 weeks doesn't seem like that. If you want to be sure you're getting the best nutrition possible rather than empty calories, your doctor might advise you to check the sodium content of your diet more carefully or try a few food switches.