I have here attempted to create a race that is to humans and half-humans like Eladrin is to elves. I am slightly worried that it is overpowered and if it is, please let me know how I can fix it.

Faetouched

Ability Score Increase. Your Charisma score increases by 2.

Age. Faetouched mature very slow compared to humans, reach the
maturity of a 20 year old by 200. They have been known to live up to
1250 years.

Alignment. Most faetouched are chaotic due to the wild nature of there
heritage and seelie faetouched lean towards good while unseelie are
usually neutral or evil, but there are exceptions.

Size. Faetouched stand between 4 and 6 feet tall and have slender
builds. Your size is Medium.

Speed. Your base walking speed is 30 feet.

Darkvision. Used to the twilight of the Feywild you have darkvision
with a range of 60 feet.

Faerie Cunning. You have advantage on saving throws against being
charmed or frightend, and magic can't put you to sleep against your
will. In addition you suffer no memory loss upon leaving the Feywild.

Languages. You can speak, read, and write Common and Sylvan.

Subrace. Faetouched are divided by which Faerie Court they have a
stronger connection to. Choose one of these subraces.

Seelie Faetouched

Ability Score Increase. Your Dexterity increases by 1.

Protection of the Summer Court. You have resistance to fire damage.

Blessings of the Queen of Summer. You know the produce flame cantrip.
When you reach 3rd level you can cast the faerie fire spell once with
this trait without using material components and regain the ability to
do so when you finish a long rest. When you reach 5th level, you can
cast the charm person spell as a 2nd-level spell once with this trait
and regain the ability to do so when you finish a long rest. Charisma
is your spellcasting ability for these spells.

Unseelie Faetouched

Ability Score Increase. Your Constitution increases by 1.

Protection of the Winter Court. You have resistance to cold damage.

Blessings of the Queen of Air and Darkness. You know the thaumaturgy
cantrip. When you reach 3rd level you can cast the Snilocc's snowball
swarm spell once with this trait and regain the ability to do so when
you finish a long rest. When you reach 5th level, you can cast the
darkness spell once with this trait and regain the ability to do so
when you finish a long rest. Charisma is your spellcasting ability for
these spells.

Balanced and ready for playtesting

I'm going to use Detect Balance to assess how powerful this race is. This tool assigns scores to various racial features based on how useful they are. A good homebrew race should score between 24 and 27 and should never exceed 30. Here's how the calculation comes out for your race:

With a score of 27 your class is exactly where is should be in balance terms. Both your subraces have identical features so I have just assessed them together.

There is one issue with the Blessings of the Queen of Air and Darkness spells. Normally you would gain a cantrip at first level, a 1st level spell at third level and a 2nd level spell at fifth level. Snillocs Snowball Swarm is a 2nd level spell which, in theory, makes this slightly stronger than it should be. I say in theory because SSS is a slightly underwhelming spell for its level. Still it may be good to replace this with Ice Knife to bring it in line with other races with similar abilities without changing the thematics too much.

Additionally equated the Faerie Cunning trait to the Elf's Fey Ancestry. Yours is actually slightly better with the addition of the frightened condition and the Feywild part. Makes your races slightly stronger than detect balance would indicate but still within fair bounds.

I like the theme of this race and the abilities work well together. This is ready for playtesting, and I doubt you will encounter any issues.