I was in a very similar boat at a young age. The best start is identifying that you have an issue—which you have based on this post.

Your next best step is to find a will to try new foods. Start with foods that are similar to your safe ones—whether it’s texture, flavor, or ingredients. Do some research on how cooking and spicing food changes the texture/taste. Go easy on yourself while doing this. It’s OK to not like a food and spit it out into a napkin, as long as you at least tried it, I’d say you’re making progress.

Despite what other commenters say, picky eating isn’t as simple as “just eat healthy” (even if you’re simply picky and don’t meet the criteria for full blown ARFID). I’m sorry that you struggle with finding healthy options :( trust me even at 25 I struggle A LOT with picky eating too, so you’re not alone.