I'm building a character idea and I'm trying to get away from the tribal warrior stereotype. I currently have

Puck - Rock gnome 

A little over 200 years old, so middle-aged. He's spent his entire adult life working as a miner to provide for his wife and dozen children. They've never lived in luxury but he's always provided for them, always putting them first. He's a mild mannered, almost timid character. Over the decades working for the same employer, he has come up with countless ideas to increase the mine's efficiency. Year after year he has been rejected for promotions, getting passed up for the boss's many nephews and cousins etc.

This continues until the day of his and his wife's 200th anniversary. He asked one of his fellow miners to cover his shift so he could leave early. On his way home he picked some flowers, purchased the finest wine, some fine jewellery. He arrived home and finds his wife packing a suitcase. She says that after 200 years, he's still just a common labourer, she's tired of their standard of living and she deserves to be treated like a princess and have nice things. Confused and terrified, he begs her not to leave and she laughs in his face and responds 'I'm not leaving, you are!'

She throws him the suitcase and pushes him out the door just in time to see his boss approaching. Desperate, he begs his boss for help but is ignored. He walks right past, winks at Puck, then grabs and kisses his wife, closing the door as she pulls him towards the stairs. Desperation turns to horror as the last 200 years of his life flash in front of his eyes and Puck realises than none of his 12 children look like him. It is in this moment that he enters his first rage. Taking up his mining pick, he smashes through his own front door and heads upstairs. Several minutes later he walks back out the front door, dragging his bloodied, limp, half-naked boss by the beard. 

Homeless, unemployed and harbouring a whole new disposition, Puck decides 'F**k this, I'm outta here'. Thus begins his adventuring career.

I'm picturing a grumpy, surly gnome who rages at the drop of a hat. High intelligence, decent strength and constitution as he was a miner for 2 centuries, okay dex and wis but terrible charisma. Gives absolutely zero f**ks about people's feelings.

 I like the idea of him dual wielding, the image of a little gnome just going mental with a couple of short swords makes me chuckle. Maybe have a war pick as a back up weapon. I can't decide what subclass would fit though.

Any thoughts?

Hmm .. I can imagine who snapped and went full on Fight Club. Chaotic Neutral (Evil?), Guild Artisan Background, proficiency in Blacksmith's Tools (I know he's a miner, but he could very well have picked up the rudiments of metal work as a related field) so he can weld nails to armor and become a Battlerager (ask your DM to approve a non-dwarf). I don't really see any other Path than Battlerager or Berserker for this character since his rages don't touch on anything particularly spiritual. But he can use his tool proficiency to become a sapper, sabotaging the industry and society that betrayed him.

I know you mentioned not the totem barbarian, but flavoring them seems to fit the best. Take wolf at lvl 3 to give your allies advantage because a gnome swinging 2 short swords that strongly is distracting. take Elk at lvl 6 because you want to get as far from your ex-wife as possible. and take and bear at lvl 14 because you are so intimidating. 

Or keep watching Unearthed Arcana for a subclass that fits your style better.

Maybe you can just take a subclass you think is fun and re-flavour it to his situation, for example a Wild Soul that got infused with magic because of something in the mine he worked at, the rage - when the wife kicked him out - being the final trigger. Or a Totem Warrior that has a picture of his children as the totem.