Learn English – How to use ‘even so’

This sounds like a personal preference rather than anything to do with the way English is actually used. It was good enough for such talented writers as Robert Louis Stevenson:

Already in our society . . . the bourgeois is too much cottoned about for any zest in living.

and Betrand Russell:

Already in December 1676 Leibniz held that not all possibles exist.

No, it is not valid (well, natural) English to say or to write:

• No, ∗sure I am not.

It would be understood, but it doesn’t sound at all right. It would mark you as a non-native speaker.

The closest to what you are talking about would be the very archaic and/or poetic-sounding full inversion:

• No, sure am I not.

I suppose you could say that if you really wanted to, but it sounds completely affected. It really stands out. It’s not normal speech, although neither is it “illegal” as your first one nearly is. Maybe you could use something like this for the very rare and special occasion:

• No, “certain” is very most definitely something that I am not!

That doesn’t sound normal either, but it might be used to draw attention to the first word. Regular speech would simply be:

• No, I’m not sure.

or sometimes,

• No, I’m not sure, either.

Or if someone else had just said that they weren’t sure, then you could respond with and of:

• No, I’m not, either.
• I’m not, either.
• Neither am I.

Notice the inversion in the last one.

Notice also how unlike in German, you cannot in English use “too” or “also” in the negative: you must use “not . . . either”, or less commonly “neither” followed by subject–verb inversion (that is, verb–subject). This last point I mention because is a very common mistake that native speakers of German often make in English, and some possible answers to your question might lead you down the wrong path.