Thank you for you comment.
Building removing all power consuming elements is one of the keys. For low power you cal remove all regulators and DC power converters if any. Powering with 2 AA/AAA provide 3V which can be fine, but take space 😉
The DHT11 is not the best sensor since it's slow and consuming power during conversion but with 2 AA/AAA it should works quite long as soon as you disable the sensor during low power sleeping mode.
For ULPNode I'm working also on Gateway, currently an Arduino like but still testing with Spark Core / now particle and even ESP8266, they have more flash/ram add allow the gateway to do some other things such as displaying on a LCD/OLED
Humm, that's interesting, I already fixed a problem with negative values in library (see ). As far As I remember this fixed the problem (but may be it's another issue now)
Are you using the latest version ?