Sindarin 

guren

noun. my heart

Apparently the word gûr.1 with a suffixed possessive. See lammen for a similar form

Sindarin [VT/41:11] gûr+-en. Group: SINDICT. Published by

guren bêd enni

my heart tells me

nín

my

(following a noun with article: i adar nín, ”my father”). Not to be confused with nîn ”watery, wet” or as noun ”tear”, or the pl. form of nên ”water”. – In a very few attested cases, the pronoun ”my” appears as an ending -en added to a noun (lammen ”my tongue”, guren ”my heart”).

gûr

noun. heart (inner mind)

A word for “heart (inner mind)” in notes from the late 1960s, equivalent to Q. órë (VT41/11). In the original article published in VT41 in July 2000, Carl Hostetter gave its primitive form as ʒōrē, but in his later book The Nature of Middle-Earth published in 2021, he corrected this to gōrē (NM/219).

Conceptual Development: Early Noldorin word-lists from the 1920s had N. gir glossed “interior, centre, inwards, inner parts” (PE13/144) or “inwards, interior, inside, heart” (PE13/161).

Quenya 

hondo-ninya

my heart

hondo-ninya noun "my heart", changed to indo-ninya (FS, earlier version)