Hi. We have a 13 week old Shih Tzu pup, and have had him now for 4 weeks. It's been an up-and-down time for me, with moments of enjoying it and moments of wishing my life could go back to the relative ease of how it was before. He is absolutely gorgeous, but it's hard work and no mistake. The toilet training is just awful. I'd say it ends up on the puppy pad 50% of the time, rest of the time on the floor. My mum recently visited and commented that she thought we had too many puppy pads out; there was maybe one or two in each room. It's difficult because we're in a flat (with its own garden) all on one level, so it's not like I can shut off the upstairs or anything like that. So he probably does have too much of a run of the place (albeit under a watchful eye!). Any advice on where to go from here?
However the main reason for my post is his growling. Don't get me wrong, he doesn't just look at us and growl, so there must be a reason in his head! It happens often when he is picked up (he's still very little, so sometimes obviously has to be gently picked up) and pretty much every time his harness is put on. It goes without saying that he is treated very well, gently and with kindness. My daughters are aged 14, 9 and 6 and all are very good with him ... and adore him. I am worried that one day he will snap. Ironic really, as I picked this breed for their soft personality, yet the wonderful Staffies that we had as kids never once growled at us 
Lastly, his separation anxiety. If he's sleeping on the sofa, and I leave him to fetch something from another room, he will wake and bark to be let down. He hates being left on his own, and it's exhausting.
I sometimes wonder if he's happy with us. He loves meeting new people, but is quite a serious wee chap. He doesn't tend to get excited to see me, and a tail wag has to be worked for!
I do love him, but sometimes just don't feel very bonded, and these issues aren't helping. I've sometimes wished over the past few weeks that I could go back and do things over, in an improved way. I've probably made so many rookie mistakes and this hasn't helped things either. A puppy is a lot of work for a single mother of 3 kids with no family living nearby, a home to run, also a cat etc. Still, this is what I signed up for and I'm determined to make it all work. I'm not ashamed to admit that it's just harder than I thought it would be and I have a bit of depression, which may be clouding my thoughts and judgement a bit.
Any thoughts or advice would be very much appreciated. Thank you.