I'm uncircumcised and i have a piece of skin between my foreskin and tip and a doctor told me it isn't normal should i be concerned?

No: What you are describing is a residual adhesion of the inner foreskin to the coronal margin (outer rim) of the glans (head) penis. These adhesions are normally present and circumferential at birth and then spontaneously breakdown during early childhood but can persist into adulthood. Unless they are of some bothersome cosmetic concern, they are of no significance and no treatment is required.

Not abnormal: It is the penile frenulum, similar to web under the tongue. It connects the foreskin to penile glans just below urinary opening. It helps to return foreskin back to cover glans. It can be abnormally tight causing pain upon foreskin retraction, during sex or with masturbation. Abnormal tight frenulum can be corrected by frenulotomy or release with a transverse incision sutured transversely.