Green card waiver

Hi I am not sure how to start a new thread and I'm sorry if this is messing this one up.
I am 36 and went for my green card interview last October in Dublin. I was refused on the grounds of a conviction for Larceny/damaging a property 22/9/1999 but which happened when I was 17 and conviction for criminal mischief with intent which isnt worded on any of my court papers but now they seem to be saying its for an assault in 2001, the larceny/damage to property was basically I broke the window in my neighbours car and stole a VCR, I called to the neighbour the next day and returned the VCR but the cops were already involved and the fight was just a silly thing between drunk friends one night and no one was hurt. Now I am not trying to make light of the two convictions but the 1999 Larceny/damaging a property case was discharged conditionally on my entering a recognizance and paying a 100 pound fine. The assault which my lawyers say could be argued isnt CIMT was a Section 2 of the Non-Fatal Offences Against the Person Act, 1997 in irish law and the out come was 6 months suspended Sentence, This assault was with another guy my age, we had a fight and the garda (cops) came and arrested me, the guy (who is a friend) wasnt in anyway hurt when this happened.

My lawyer tried to get the embassy in Dublin to relook at the case arguing I should not be deemed inadmissible under 3 arguments:
-Under 18 years when crimes committed
-Petty Offence Exception
-Juvenile delinquency interpretation

They wouldn't have any of it and now I can only apply for a waiver, the only thing is my mother who has us citizenship for the last 20 years and lives in Boston isn't in any way sick of financially in need of me being there and so it would be hard for me to show extreme hardship on her part. My lawyer is saying the only way to try is for my mother to see a therapist for her depression and get a report to send with my waiver. I just would like to know has anyone heard of this being used successfully and if anyone would have any kind of info on this.

all this stuff happened nearly 15-20 years ago now. I've lived in Australia for two years and London and have never been in any trouble as well as spending many 3 month holidays in the usa at my mothers without anything.

I just don't have loads of money and really only have one chance of doing this, I have to help out my family on my father's side in Ireland as he is unable to work now.

I really just need some info on if it is worth trying for this waiver or if I should just give up on this and use the money to get a waiver which is easier to get so I can have holiday visas and still visit my mother in the usa like I did before. But one lawyer said she didnt think I would even get this now because I went for an immigrant visa while another lawyer said I could get this holiday waiver. Its just so hard to know what to do, if anyone has any advice on this it would be great as I am just not sure what to do now.