I'm not sure that complimenting their looks is the best way to reassure them. I know its well intentioned but it reaffirms the importance of physicality. For reasons you've mentioned, this a complicated and very emotional area so any compliment is likely to raise difficult and painful feelings. I would focus instead on traits that are less complicated for them - intelligence, inner strength, resilience, creativity, helpfulness to others... Build up their sense of value not based in perceived gender parameters.
I would also take a step back with regards to counselling. I wouldn't be surprised if the more its "pushed" the more your child resists. Have the offer and suggestions there but when they ask for it. It might give them more space to work out what will help them and to maintain their autonomy while they do so.
The trip to Italy sounds wonderful and while I agree you should both consider male attention id let it be your dd/ds choice to go or not. Firstly, they take control that way, which they clearly need and secondly it gives them something to look forward because if not Italy then see where else they'd like to go.
(I've been to Italy alone a few times btw and never been catcalled or treated with anything but respect by Italian men there.)
Regardless of whether they are or are not, truly trans, I wonder if they'd benefit from more strong female role models in their life? While you are clearly one yourself, as mum you're emotionally invested in a way no one else is and other female relatives are disparaging. Add to that a brother with a strong character and your child's attack..regardless of their true gender it happened while in a female body and so it's fair to say, as you have, that their feelings about womanhood have been compromised.
Honestly, I'd be seen to step back with regards to their gender identity. That isn't to say your worries are not valid and shouldn't be explored - they are and they should. But if your child feels safest and happiest identifying as a boy, then being seen to debate their identity or choice is only going to make them feel unsafe.
If it turns out they later change their mind about how the express their gender identity, then fine, and likewise if they don't. If they ask you tell them your concerns but if they don't then I would suggest something more along the lines of "look i have worries, because I'm your mum and its my job to consider all possibilities and id like to be assured that you're informed but I fully support you whatever you do or don't do in the future" and leave it at that.
If they're at all unsure about where they fall in terms of binary gender definitions or somewhere along a spectrum, im not sure that involving yourself in the debate will help them. I think they'll just feel less safe and more likely to lean on friends.
A lot can change in the next few years - your dd/ds is going to grow up, hopefully find their voice, probably make new friends and inheriting money at 21 is still a way away. I would trust that for someone as intelligent as them by that time they'll have done a lot of research and be more assured in what is right for them to do, whether that'd to pursue surgery or not. Focus on letting your dd/ds find their new place in the family dynamic now that brother has moved out.
I'd also look to see if they're interested in self defence classes, useful whoever you are but especially empowering if you've been threatened. Focus on helping them feel empowered in all areas of life.
There was an interesting AMA a while ago, written by a woman who's child is transitioning, it might be worth checking it out and maybe seeing if she's still around to chat to. I think they went through the full gamut of emotions too.