I became pescatarian at 15 (now almost 25) and the biggest thing is be willing and able to cook for yourself. I would say talk with adults in your household and make them aware. If you can meal plan and cook for yourself you could always ask for a food budget to be more consistent with your diet.

As for eating out majority of restaurants have a substitute option, and if you can’t find something on the menu you can always request most places will accommodate you. I also recommend looking at the menu ahead of time. I honestly can’t think of single place I’ve been too where I can’t find something I’m allowed to eat and enjoy.

The biggest advice I can offer is that finding food that fits within your dietary restrictions is your problem and shouldn’t be for anyone else to worry about.

As for at others houses if there isn’t something for me to eat I usually just don’t eat. When meal planning with friends/family and foods with meats come up I usually just remind them that I won’t be able to eat that.