This is a follow on from another thread where I'd posted an image gallery of my picea "over the years" and some commented that my tree is not looking so good lately, so thought best to start a new topic in this section, which is more relevant than just the photo sharing one (hope that's OK and makes sense?).
Last September I took "Harry" (my picea) into my local bonsai guy and he told me I had to spray it with pesticide as he was under attack by some caterpillars. All the buds had been hollowed out and there were a few strings of thread, from the little terror. So I've been spraying him every two weeks up until end of December (as instructed) but after some other opnions.
My once lush green picea has been struggling for the past 12 months, going less vibrant green and lush to a duller and thinned out (not unlike my hair). As above, I put this down to un-invited guest(s). In the last month or so the branches on the southern side (right hand of first image) have lost their leaves. Some of the branches have dried out and the ends snap off easily.
Could it be I'm not watering it enough. The soil never seems to dry out, and water passes through quite well but I've been only watering once-twice a week, as I'm worried he's too moist. Also suspect too moist as the moss/weeds grow quite well and I occasionally pick them away.

I haven't worried too much as I have one or two branches which are growing as expected, giving me (false?) hope that he'll be OK.

Then the other side looks so desolate it's driven me to posting these images, as I'm a little lost at what to do.

Keen to hear any idea, thoughts, suggestions, etc.
- Daniel
p.s. I have been adding dynamic lifted since September also to boost him along through Summer.