You can usually tell RCs have become a habit if you do them often without needing an external source (like a phone alarm) to remind you to do them - you just naturally do them throughout the day, provoked by something odd you notice, or maybe even just the feeling that you should be doing them.

As for techniques not working, it's fairly common for what's known as a "dry spell" - where anything from dream recall to technique effectiveness can drop significantly for anywhere from a couple days to a few months. The important thing when in a dry spell is to not get discouraged, and continue to stay dedicated to your practice. Focus on the light at the end of the tunnel - how fantastic it will feel when you finally do have another lucid dream, knowing you've conquered your dry spell.