Hi Maya_Fantasy,
I really do not have much expertise on makeup but I would like to comment on your question

.
Since you have round eyes & somewhat of triple eyelids and your lashes are a little fine. I think a little makeup on will enhance/beautify your look more, especially if you will be taking lots of pictures at the wedding and weddings are events mostly everyone will want to look their best

, a little makeup will help you look prettier

.
I would do both, applying mascara (curl the eyelashes too) & applying eyeliner too. If you think it is too much makeup then do which ever you see your eyes need more. I have a good amount of eyelashes on both eyes but they are not dark, long & curl so when I go to special occasions & I know pictures will be taken I apply both mascara (curl my eyelashes too) & eyeliner. I would also apply a little bit of eyeshadow that match with the dress I am wearing. Depending on my moods & if I want my eyes to stand out more sometimes I would do eyeliner on my bottom eyelids too. I provided charts above, I think they will help you on putting makeup on your eyes except how to apply mascara & curl the eyelashes.
I use Almay black liquid eyeliner & NYX from Nordstrom Rack retractable eye liner. I don't specifically use any brand for mascara and the eyelashes curling thing (hehe, not sure what it is called) since I hardly do mascara & curl my eyelashes but you could easily buy them at any retail store.
The eyes are very important & the first things people tend to notice each other are the eyes, as people say they are the windows to the soul hehe so I think you should enhance/beautify them. Good luck & I wonder how your eyes will look if you decide to put makeup on them hehe

.