Thank you very much for the answers.
By the way, I have already spoken with the construction manager. He basically even confirmed to me that Helma should pay some compensation for the monthly damage incurred. Of course, he could not quantify the amount of compensation. Moreover, this is so far only the opinion of the construction manager and does not necessarily reflect Helma's position. It is therefore also possible that Helma will not pay any compensation at all.
Of course, Helma is not responsible for the delivery delay. Neither am I, however. Since I now have to service the loan I took out, and the costs for my living expenses as well as electricity and gasoline have risen exorbitantly (and will probably continue to rise), I would be very grateful for any relief, no matter how small. So if I am legally entitled to compensation, I will enforce it. I did write that I have been satisfied with Helma so far, but of course Helma has not given me anything in return either and has strictly adhered to every single contractual detail.
One additional piece of information: If the handover of the building is delayed by more than 2 weeks now, Helma is obliged to pay compensation anyway due to the failure to meet the contractually agreed construction period. Therefore, Helma is very keen to carry out the handover quickly now.