The chapters do all have 18 pages but the content within each chapter are getting more and more shallow. Either the mangaka is intentionally going for the increased suspense or he's just milking the series. Either reason points to a ending coming sooner and later.
Japanese weekly magazines have reported that Kouji Seo is working on the publishing on his next project - meaning Suzuka will most likely finish within 2 volumes and since we are in mid volume it's logical to guess that Suzuka has 14 or so chapters left.
On another note: Reading the criticism-full chapter threads aren't so bad. You see other point of views that you normally wouldn't see yourself. Well, past the constant incoherent paragraphs and horrid grammar at least. Hell, it was more interesting trying to understand the characters rather than reading about Suzuka and her daily menstrual cycles and Yamato's amazing ability to neuter himself.
Maybe the chaps look shorter because this manga is so f-ckin awesome.