You haven't said whether you've done much programming before getting involved with Node-RED, MQTT and ESP8266's, but if you have a bit of C++ ability you can fairly easily "roll your own" simple sketches to read sensors, control actuators etc.
You've already included PubSubClient which will handle all the MQTT stuff for you, so it's just a case of sending and receiving messages at both the ESP8266 and Node-RED ends to get things working.
(Yes, that's a little bit of a simplification, but it really is quite straightforward 
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