Why do i face problems while speaking english? :(?

Forgive yourself for not being perfect and learn patience. You are only 15! Everybody faces problems when learning a second language. Some people still make grammatical errors of 35 years of speaking a language, but they don't make the bad choice of getting discouraged and feeling sorry for themselves over it. Schopenhauer once said, "We cannot always choose our cirstances, but we can always choose our attitude toward them." In your case, you can choose both. Once you relax, your English will improve immediately.