8 minutes improvement may not seem a lot, but it is! especially for someone who started just before christmas.
how far can you go in 8 minutes? well given your current speed, a little over half a mile! a surprisingly long way really.
Don't put yourself down, if you had got worse then be worried but as you have improved give yourself a pat on the back. 
in answer to your question, you have already got faster - keep up the training and you'll get faster still.