14yo solo dev - built NextSap but struggling with retention

hey indie hackers

im 14 and just launched nexsap.com after coding it solo for months

the idea came from hating ads everywhere online. i wanted to make product discovery actually enjoyable instead of annoying

nexsap is basically a social feed where people post their content and products and others discover them organically by scrolling. no forced ads just natural discovery

built it with flutter and firebase. got ebay api integrated and works in 10 languages

i made an android app too but cant focus on it right now cause i dont have money for ios developer account

heres the problem tho

getting traffic to the website from twitter instagram facebook but literally 0% retention. people visit once and never come back

i think its the cold start problem. when new users open it theres not much content yet so they just leave

questions for you all:

- how did you solve cold start for marketplace/social apps?

- should i focus on getting sellers first or just fill it with content myself?

- what makes you come back to a website the next day?

this is my first real product so any advice would be huge. im good at coding but the growth/retention side is totally new to me

thanks for reading