Since you are a trainee, I don't think they will agree on something more than what they have already offered. Also, you are living with your parents and as such you do not need to worry on accommodation costs. Frankly, while some people may tell you not to accept the offer, I would advise otherwise. I am basing my advice on my own experience when my first job was paying me a very poor salary. However, I took the job and after I had loaded myself with valuable hands-on experience, I came to a point where I could negotiate and landed myself a better paying job.