I have pain in my shoulder when i lift my arm above my head and stretch it upward. the pain is not severe, however it impedes me from performing shoulder/bench press. it's as if there is no strength in my shoulder. is it a rotator cuff issue?

Likely tendinitis: Pain with overhead activities in young adults is less likely a frank rotator cuff tear and more commonly bursitis or rotator cuff tendinitis, both amenable to rehabilitation, rest, NSAIDs. An MRI may become indicated for recalcitrant symptoms. An orthopaedic evaluation would be very beneficial. You could also have a superior or posterosuperior labral tear (SLAP).