This is normal. I guess we get this randomly. Sometimes we have a lot of LD's, then they stop, then we get them again.
Take my example. Normally i have 1 LD per week and around 3 non-lucid dreams daily with great recall. Then all of a sudden, for 3 weeks, all of my dreams stopped. No recollection whatsoever. And then, the 15 days after that i had 13 LD's(!!). You see? It's not constant. And it helped not being frustrated. I thought: "I had no dreams again. That's ok. They will come back." And they did.

So, my suggestion is: don't try so hard and don't be frustrated by not having the dreams you like. When you least expect it, they will come back.