Before giving a reply you have to explain more things:
Purchase price ?
What and how much do you mean by a deposit ?
Have you carried out stage payments ? How much money ? Do you have BGs ?
What was the exact wording of the contract for the delivery date ?
Where is the property ? This is important to know what laws apply etc…
Litigation 6.000 Euros ? That’s only the start IMHO, although I’m personally not specialised in litigation it can triple that amount in a few years time because the developer appeals the court rulings and the case drags on and on. You better make absolutely sure what you are doing before litigating in Spain.
Lawyers cannot normally give a starightforward answers before reading your contract. Every contract is a world to it’s own and must be read and analysed carefully. Depending on some developers, i.e. Sofia, even If the wording of the contract is right you still have to resort to litigation so your lawyer maybe perfectly right taking litigation for granted.
However, you ought to know that your developer is obliged to compensate you under Consumers Law for not including the swimming pool.