Help with what to wear?

i am a 19 year old male and i am attending a wedding on saturday. the wedding is at a winery that is on the water (with beach). the ceremony is all outside, and the reception is in a tent. the only thing that i am having trouble with is picking an outfit. i thought i had picked a good one, but i am beginning to think that it's a little too casual. the outfit was black dress shoes, black pants, a white dress shirt that is made for semi casual occasions (i think) and a black tank underneath and the dress shirt would be unbuttoned but tucked in. if you do agree that that outfit is too casual, any recommendations on what i could wear? i have a suit just in case i don't find anything, but i really didn't want to wear it. i want something that looks fashionable and "cool" but above all, appropriate for the occasion. thanks!!!!