If you prefer [name_f]Lucy[/name_f] to [name_f]Lucinda[/name_f], I would suggest just using [name_f]Lucy[/name_f]. The only reason to keep a longer name option would be if you want the option of having a longer, fuller name for future use and/or you want a name option other than [name_f]Lucy[/name_f] that people close to you can use.
Personally, I like the longer name option as opposed to a a hyphenated name option, especially with the name [name_f]Lucy[/name_f]. [name_f]Lucy[/name_f] can hold its own as a name, and it is distinct enough that it is hard to pair with another name as a joint first name. Still, there might be a winning combination that works for you!
Still, if [name_f]Lucy[/name_f] feels like your name, would it be awful if you were named [name_f]Lucy[/name_f] while your niece was named [name_f]Lucia[/name_f]? Of course the “[name_f]Lu[/name_f]” sound is the same and they share the same nicknames, but I would see it is a great way to honor family connections, and it makes for a great story that you can share with your future niece about how much love you have for your shared names. That sounds great to me, unless for you this causes too much anxiety or heartbreak.
Hypenated Names …
Note: These are names that stood out on your list or hypenated names that I think could work.
[name_f]Lucy[/name_f]-[name_f]Anne[/name_f]
[name_f]Lucy[/name_f]-[name_f]Bea[/name_f]
[name_f]Lucy[/name_f]-[name_u]Blair[/name_u]
[name_f]Lucy[/name_f]-[name_u]Bliss[/name_u]
[name_f]Lucy[/name_f]-Bloom
[name_f]Lucy[/name_f]-[name_u]Brett[/name_u]
[name_f]Lucy[/name_f]-[name_u]Bryn[/name_u]
[name_f]Lucy[/name_f]-[name_u]Cai[/name_u]
[name_f]Lucy[/name_f]-[name_f]Cait[/name_f]
[name_f]Lucy[/name_f]-[name_f]Cate[/name_f]
[name_f]Lucy[/name_f]-[name_m]Cove[/name_m]
[name_f]Lucy[/name_f]-[name_f]Dawn[/name_f]
[name_f]Lucy[/name_f]-[name_u]Day[/name_u]
[name_f]Lucy[/name_f]-[name_f]Dot[/name_f]
[name_f]Lucy[/name_f]-[name_f]Eve[/name_f]
[name_f]Lucy[/name_f]-[name_f]Faye[/name_f]
[name_f]Lucy[/name_f]-[name_f]Faith[/name_f]
[name_f]Lucy[/name_f]-[name_f]Fleur[/name_f]
[name_f]Lucy[/name_f]-[name_u]Gael[/name_u]
[name_f]Lucy[/name_f]-[name_f]Gail[/name_f]
[name_f]Lucy[/name_f]-[name_f]Glynis[/name_f]
[name_f]Lucy[/name_f]-[name_f]Gwen[/name_f]
[name_f]Lucy[/name_f]-[name_f]Hilde[/name_f]
[name_f]Lucy[/name_f]-[name_f]Hope[/name_f]
[name_f]Lucy[/name_f]-[name_u]Jai[/name_u]
[name_f]Lucy[/name_f]-[name_f]Jane[/name_f]
[name_f]Lucy[/name_f]-[name_u]Jay[/name_u]
[name_f]Lucy[/name_f]-[name_u]Jem[/name_u]
[name_f]Lucy[/name_f]-[name_u]Kai[/name_u]
[name_f]Lucy[/name_f]-[name_u]Kit[/name_u]
[name_f]Lucy[/name_f]-Lei
[name_f]Lucy[/name_f]-[name_u]Leigh[/name_u]
[name_f]Lucy[/name_f]-[name_f]Liora[/name_f]
[name_f]Lucy[/name_f]-[name_f]Liv[/name_f]
[name_f]Lucy[/name_f]-[name_f]Loa[/name_f]
[name_f]Lucy[/name_f]-[name_u]Lyn[/name_u]
[name_f]Lucy[/name_f]-[name_f]Lynde[/name_f]
[name_f]Lucy[/name_f]-[name_f]Lysa[/name_f]
[name_f]Lucy[/name_f]-[name_u]Merle[/name_u]
[name_f]Lucy[/name_f]-[name_f]Neve[/name_f]
[name_f]Lucy[/name_f]-[name_u]Page[/name_u]
[name_f]Lucy[/name_f]-[name_f]Paige[/name_f]
[name_f]Lucy[/name_f]-Pier
[name_f]Lucy[/name_f]-[name_f]Ruth[/name_f]
[name_f]Lucy[/name_f]-[name_u]Sage[/name_u]
[name_f]Lucy[/name_f]-[name_u]Saige[/name_u]
[name_f]Lucy[/name_f]-[name_u]Scout[/name_u]
[name_f]Lucy[/name_f]-[name_u]Shea[/name_u]
[name_f]Lucy[/name_f]-[name_u]Shay[/name_u]
[name_f]Lucy[/name_f]-[name_m]Sol[/name_m]
[name_f]Lucy[/name_f]-[name_m]Wit[/name_m]
[name_f]Lucy[/name_f]-[name_u]Whit[/name_u]
[name_f]Lucy[/name_f]-Zeal
Longer Names that Could Be Shorted to [name_f]Lucy[/name_f] (Other than [name_f]Lucinda[/name_f]) …
Liusaidh
Lumira
Luppenea
Luneve
Distinct Names that Could Have [name_f]Lucy[/name_f] as a Stretched Nickname …
Note: These names could be complimented by a middle name that when combined with the first name makes [name_f]Lucy[/name_f] a more clear nickname choice if the “[name_f]Lu[/name_f]” and “cy” sounds if they are not prominent in the first name. These could also be middle name ideas. These names may be far from your preferences, but something could work!
[name_f]Adelice[/name_f]
Alice
Alicka
[name_f]Alycia[/name_f]
[name_f]Elysia[/name_f]
[name_u]Felice[/name_u]
Felicey
[name_f]Felicia[/name_f]
[name_f]Felicity[/name_f]
Flicka
Julica
Kalica
[name_f]Larissa[/name_f]
[name_u]Larkin[/name_u]
[name_f]Laurel[/name_f]
Laurian
[name_f]Lilac[/name_f]
[name_f]Lilah[/name_f]
[name_u]Linden[/name_u]
[name_f]Liora[/name_f]
[name_f]Lore[/name_f]
[name_f]Loria[/name_f]
[name_f]Louisa[/name_f]
[name_f]Lovisa[/name_f]
[name_f]Lulah[/name_f]
[name_f]Lumi[/name_f]
[name_f]Lumi[/name_f]
[name_f]Lux[/name_f]
Lyanna
Lycaste
Lydian
Lyris
Lyrisa
[name_f]Lysa[/name_f]
Lysithea
[name_f]Millicent[/name_f]
Roselica
Ulicia
Walice
[name_u]Wallis[/name_u]