I know that "I'm sorry" translates into Irish as Tá brón orm, but how would I say "I am very sorry"?

Since the Irish translation literally means "Sorrow is on me", it doesn't feel right to say "very sorry" by simply putting an in there somwhere.

My first guess would be Tá brón mór orm (Big sorrow is on me), but am not sure about that.
What I'm trying to convey is a a sense of sorrow and remorse for one's previous behaviour.
Any help and suggestion would be appreciated.

There's nothing wrong with:
Tá an-bhrón orm.

Really? That simple?
In that case, would "I'm very sorry for my behavior" be
Tá an-bhrón orm do m'iompar

Thanks again.

(sorry) for / about: faoi or as

Tá an-bhrón orm faoi m'iompar.