Am 25 years old but still have hard slighly big nipples

I first noticed that i had hard and big nipples when i was around 13/14 years old.At first it kinna hurt when i try to press it hard and was worried,but was told it was perfectly normal and common among boys my age( sign of boys becoming men).I am 25 years old now ,am not fat and never been fat but i still have them,the only changes is that it doesnt hurt any more like when i first had them.But am still worried beacuse all my friends had them but theirs have all dissppeared and they ve well defined chest.I have tried push ups but as my chest keeps building up so does my nipples.I feel ashame to take off my shirt infront of people because my nipples look a bit big ( like a young girl s breast).Am really worried and have no idea what to do,please do advice