Commonly, we would equivalently say "This is all my own **work**", for singular, or, "These are all my own work", for plural.

Yes, you can use "achievements" instead of "work", but then drop the "all" and the "own" from the above sentences.

That's not to say that your expression is incorrect, but it isn't as easily understood by native speakers of English as the equivalent expression provided above. 

#TL;DR

It doesn't make *much* sense to use your particular expression.