Re: drying up....have low supply to begin with...stopping bf
hi mama, i wonder what makes you think your supply is dropping? it's very common for people to think this right around they point you're at - 3-4 months. things that are NOT signs of dropping supply: no longer feeling engorged, no longer leaking, no longer feeling a letdown. 4 month olds often start waking more at night when they used to "sleep through"; this is very common (teething, milestones).
nursing LESS often IS something that will lower your supply. if you're nursing every 2.5-3 hours, that's probably at the low end of how much babies this age nurse. more frequent nursing (including nighttime) will generally increase supply, even if as you say it's not a full nursing. remember boobs aren't bags; they don't really "get empty" or "fill up".
i can see why you're tired and frustrated; nursing + pumping + sns is exhausting!!! but like djsmom says, it sounds like you're actually doing an amazing job with it.
Nursing, pumping, cloth-diapering, babywearing, working professor mama with the awesomest SAHD ever.