I'll try to summarize what I've read here. Let's see if I understood it correctly:
In 2015, you discussed/agreed with the developer which paving should be done. This paving of the sidewalks and the garage driveway was only partially carried out after 15.06.2016 (at your insistence). Actually, your terrace was supposed to be built by 15.06.2016 as well. However, this did not happen – you had not even received an offer for it by 14.06.2016. You used this opportunity to change the terrace slabs again. This change is cited by your developer as the reason why he could not deliver all his services (including the paving) on time (which he had not performed until one day before the deadline).
You now want compensation for the delay in the paving. You are consciously excluding the terrace from this claim. There are no contractual compensation payments stated for the client in case of delays.
Well – I can understand the frustration. However, you might be using a sledgehammer to crack a nut here – especially since the partial paving was carried out with a (in my view) acceptable delay and the rest will probably come within a foreseeable time. In my view, you also lack the basis for a claim, as nothing was contractually agreed to regarding this.
Moreover – the weather conditions this year have already been mentioned. Even if you write that the past weeks were not so bad for you, there surely was also a time this year when the weather did not allow work. Such days are usually excluded from claims contractually.
Talk to your developer and try to agree on prompt completion. In my opinion, a "head against the wall" approach doesn’t help here, but rather mutual willingness to come together.