dd1 is doing really well at the moment. she is 6 now, and it has been a long hard road (especially with her drinking) on a good day now she will drink nearly 500ml - I never thought I'd see the day. We are at the stsge now where if she doesn't drink as much for a day or two, we don't panic - note it, and think "if that doesn't sort itself out, then we'll do something" but usually it's just day to day variation.
dd1 has a lot of issues with sensory things - smell especially is a problem for her. and she is quite restricted in what she eats (as in main meals) - but then she eats lots of different fruits and vegetables, so it works ok.
with the 9 months of not drinking - no, we didn't get any professional input. the most they ever said was "well, when she is ready, she will do it", or "she can't be thirsty - reduce down her liquid foods, and then she'll drink" - not much help, really!
we tried all sorts - giving her a wet flannel to suck/chew in the hhope that she'd get some liquid out of it (moderate success, but she didn't really take to it)
ice lollies - wouldn't touch them (too cold)
jelly/yoghurt had good success with, and the fruit pots form organix etc
wet foods (soup with bread crumbled into it to bulk it out - can absorb lots more liquid that way), spag bol, etc. she still eats food in sauces now, rather than separate foods, because of this.
luckily, for most of the 9 months she wasn't drinking she would still accept me spoon feeding her - woudln't have a hope now! - so could get watered down stewed fruit into her, thinned out yoghurt, etc.
we also made a game out of using a 5 ml syringe (like you get with calpol) to squirt water into her mouth - she quite liked the feeling of it. and so we might spend an hour or so getting maybe 30ml into her (oh what fun!)
she was never constipated over that time, so must have been getting enuogh liquids, but it was very stressful