How can I say this in Japanese.."I'm not beautiful, I'm just cute, that's all."?

Answer 1

the above translation was terrible.
If you're a girl, you could say あたしはきれくなくてただちょっと可愛いです。 (atashi wa kirekunakute tada chotto kawaii desu.)
僕はハンサムじゃなくてただちょっと可愛いです. (boku wa hansamu ja nakute tada chotto kawaii desu.)
Still, that's a weird thing to say in Japanese. It sounds like you're bragging.

Answer 2

Just to point out some mistakes:

1) "Kirei" is not an i-adjective, but a na-adjective.
2) "Tada" is not used in that way. Although it can mean "just", but is in the context of "ordinary; common". Eg. Watashi wa tada no hito desu = I'm just an ordinary person.

In any case, this is my suggestion:

Watashi wa kirei ja nakute, kawaii dake desu.

Answer 3

http://www.freedict.com/onldict/onldict.php
Online Dictionary Search Results :)

Answer 4

私は美しくない、すべてである私ちょうどかわいい、