Supervisor lack of knowledge
Consider forming a small study group with a few of the other students with whom you feel at least a bit of comfort. It may well be that others feel as you do, and a group in which to discuss issues, both technical and otherwise, can be good fro all of you. Three or four people is enough. If it is too big it will be less useful. It can also become a long term collaborative relationship. 

Some students thrive under minimal supervision, being able to develop their own ideas. But others, most I think, require some guidance from their advisor or or other, senior, members of the lab or the faculty. Many require a lot of guidance, especially at the start. In the US, a doctoral degree normally starts with a lot of coursework, giving you the opportunity to meet faculty and build relationships. But, I think that anywhere, it is a lot to expect that a graduate student is already so well formed that no guidance or other specialized instruction is needed. 

I don't think that you are in a hopeless situation, but you will need a plan for focusing your knowledge on the task at hand and acquiring skills and knowledge that you will need for success. Your lab-mates may be able to help you with this or at least give advice about the kinds of things that it would be helpful for you to know. Ideally your advisor should supply this, but not all are willing to do that, being more focused on the task at hand than on the students making it possible. 

Again, I suggest that you treat this partly as a social question. "How do I get more connected to those in my lab for mutual benefit?" There is more to it than that, of course, since you come from a different field, but it might make it easier in the long run. A senior member of the lab, a student close to finishing, might be an especially valuable resource - especially if a co-advisor is not possible.