I've been looking for a phd position for quite a while now (a few years) and while I've had some interviews none of them bore fruit. I have a few publications and experience. Is it really that hard to find a position? Any tips or insight would be much appreciated.

Depends on your field. Some are more competitive than others. I've known funded PhDs advertised and receive no applications.

If you're getting interviews, you're doing something right so I would keep going. If you're not successful, ask for feedback so you can check you're not making any fundamental errors in the interview.

I agree with ToL and wish you all the best - it can be so hard. Do you have a "foot in the door" anywhere so's to speak? If you're working (voluntary or paid) somewhere as an RA that can help, as they then know you and may be more likely to fund you. Also you can make sure your proposal is in line with the interests of a particular research group if you are associated with one in this way.