Suggest Remedy To Make Bones Stronger

hello, i feel like my bones are getting weaker: i get tired faster and i love to dance but i just dont have as much energy as i used to, wen i go upstairs sometimes my legs start to hurt but sometimes it doesnt. I have a problem that i cant eat alot of fat so i need to take extra care of my bones but everything i try always has a after effect which is causing me to stop taking the pill, what can i do to make my bones stronger. Oh and i'm 18 years old