In all of Tolkien's legendarium, there is only one female dwarf we know by name: Dis, sister of Thorin Oakenshield, mother of Fili and Kili. She stands in the direct line of Durin (in fact, Thorin is the last king of that line, since his heir, Dain Ironfoot, is Thror's younger brother's grandson), and as such is one of the highest ranking Longbeard dwarves.
And yes, that means she has a long beard. Tolkien stated that 'the Naugrim have beards from the beginning of their lives, male and female alike', and while she could have trimmed it, the Longbeard tribe pride themselves on their, well, long beards - the elves of Rivendell joke that they are long enough to drag in the water below the bridge!
Dis was born in the Lonely Mountain, and was ten years old when Smaug attacked - a small child by the standards of the dwarves, who didn't reach their adult stature until 40, and (if Gimli is anything to go by) stayed at home until around 60 years of age. She fled with her family to the Blue Mountains, far to the west - and there she would have stayed. Her childhood spanned the most tumultuous years of dwarven history since the fall of Moria - the War of the Dwarves and Orcs, nearly ten years of war which culminated in the cataclysmic Battle of Azanulbizar. Dis was 39 years old when the battle was won.
(To compare her to other famous characters from the Quest of Erebor: Thorin was 53. Balin was 37. Gloin was a mere child of 16, while his brother Oin was all of 25. Dain Ironfoot was 32, about as young as a dwarven warrior can be - which makes his slaying of Azog (and his glimpse of Durin's Bane) all the more impressive)
Dis' life was one of tunnels, forges, and caves. There were fewer women among dwarves than men - they made up about a third of the population - and as such they tended to stay at home. They weren't required to marry - in fact, the text suggests less than a third of the men got married, which corresponds to a quarter of the whole population, and suggests that roughly one in four dwarven women did not marry. But Dis did, and bore two sons (and potentially a daughter or two - dwarves tended to have four or less children, and didn't record their daughters on their genealogies).
There was something slightly strange about Dis' family. In every recorded case, dwarves began having children at the age of 100, within a span of maybe two years. For instance, the three famous Kings Under The Mountain, Thror, Thrain, and Thorin, were born in 2542, 2644, and 2746. And, indeed, Dis stuck to this cultural imperative - her elder son, Fili, is 99 years younger than her.
But there is another data point: the time between children. Balin and Dwalin were nine years apart. So were Oin and Gloin. Dain I, Thror's father, was ten years older than his brother Borin - and there were ten years between Thror and Fror, and nine between Fror and Gror. There were even nine years between Fundin (father of Balin) and Groin (father of Gloin).
But Thrain broke the pattern - the unwritten law. His second son, Frerin, was a mere five years younger than Thorin, though Dis at least was born nine years after him. And Dis continued this minor transgression: there are five years between Fili and Kili.
But why? One possibility is that Dis - and her father before her - broke with the tradition of Durin's line and married outside the Longbeard clan. When Beleriand was broken, the Firebeards and Broadbeams of Nogrod and Belegast were driven from their homes, and fled to Khazad-dum to join the Longbeards. We know the clans maintained their separate identities through the millennia that followed - Thrain was able to call on the 'Houses of other Fathers' in the War of the Dwarves and Orcs. Was this an alliance which had long been building - one which had led Thrain to marry outside his own clan, securing the allegiance of one of the other tribes?
The ruined city of Belegost lay very close to Thorin's halls in the Blue Mountains. Could Dis have followed her father's example, marrying into Firebeard or Broadbeam blood? Perhaps. Fili and Kili are both described as having yellow beards, which could suggest the fire of the Firebeards. They also both wear blue hoods - reminiscent, perhaps, of their ancestry in the Blue Mountains. And, of course, in the movies, they are portrayed with short, neatly-trimmed beards - hardly the grooming style one would expect of a Longbeard of the Line of Durin!