I think you might be trying TOO HARD. Sometimes it's not good to be TOO MOTIVATED. You should take short breaks everyonce in a while.
The only other problem I can think of is that you might not be getting enough sleep. You need at least 8,9 hrz of sleep every night to get better at dream recall.
You should also try taking some Vitamin B6. I've been trying that for about 2 weeks now and I can assure you that it works really well in making your dreams more vivid. Just take a 50mg B6 pill about 1 hour before going to bed everynight , you will notice the effects after abour 3, 4 days.

One more thing ... what do you actually mean by 'PRACTISING LDing' ? ... What induction methods are you using. Perhaps you're not using the methods that are most suitable for you.
Anyways , take a sure break (1 - 2 weeks maybe) and start again, but try to gain as much info. as you can about LDing induction methods and Lucid Aids , during these two weeks.

Good Luck