Don't try too hard to sound like a native, all that matters is that you can be completely understood, and you can say what you want to say. In the English speaking world, we expect all natives to have some kind of accent. And honestly, a lot of native English speakers think that different accents sound cool and interesting.

Something to think about, from south of the equator... In the recent past, immigrants who came to Australia not only learnt English, but learnt the accent. Learning the accent was their own choice and effort, and was done to fit in. I personally know several people who have done this, and their accent sounds as natural as local speakers - even though they started learning as a teenager/adult. I'll also add, this was no rare exception. Immersion in the culture helped, of course. But some people will never lose their original accent, so don't worry too much about it. You can still be considered a fluent speaker but keep a strong accent. Sometimes sounding foreign is a bonus! ;) One more thing: to speak English "like a native" is misleading. We "natives" (Brits, Americans, Australians, Canadians, etc etc) don't always share the same accent, use the same idioms, nor even use the same words. Yes we share the same language, but we can also confuse each other.

go abroad for staying there about 3 years

ME :))))))

It's not true that non-native speakers always have accents. In fact, native speakers have accents too.