The law firm you mention had a very cosy relationship with ADH which does beg the question as to whether their "new firm" is acting in your best interest.
But you need to look at big picture and see if what you are buying into resembles what you thought you were getting in terms of facilities, overall finish etc. ie landscaping etc I would be very worried about anything half completed or promises that the developer will put that right etc - will finish in due course etc. THEY RARELY DO!!!! So if the car park has no gates now it never will unless the resients pay!
The developer will try to get what he can from a few completers and then walk away and leave the bank to sort the rest out.
You need to look very closely at the community which may not yet be established and find out how that can survive without the additional phase. Without the additional phase community fees could well double? you said it was intended you would share facilities?
The other problem is the viability of the community and becuase you might find the developer will not pay community fees on unsold units and then you have big headaches trying to decide how to run the community.
I would also encourage you to confirm the pool is licensed. I have come across developments where thre is no licence for the pool and lawyers rarely check for this.
There is always a risk when being among the first to complete and move in as to whether others will follow and you definitely do not want to end up with a legal house on some half finished development becuase you will never be able to sell in the future.
Also make sure you check that the development is properly connected for water & electicity and that you have up to date bolitins for both for your property. I have seen many problems here in the past and the last thing you want once you complete is to have to pay out more money to upgrade installations to current standard to get your property connected. No builders supplies etc. etc or stories of it will all be done in due course. Otherwise any problems with the infrastucture will have to be paid for by community after developer has disappeared. ....
You should also undertake a full snagging survey before completion and there are English surveyors working in Spain.
Also make sure all the money you paid to date is reflected on escritura etc
So proceed with caution and if you do not engage another lawyer then make sure you ask a 1000 questions to your lawyer and insist upon written responses and if you do complete make sure you know exactly what you are getting into .....