Give her a gift you made yourself. It can be simply but meaningful

U could also give her phone cover!! Matching ones!! One with u n other with her!!

Your gf is really lucky then. Wow. Your family accepted her and you guys have a good relationship. SO LUCKY!!! I wish I had that luck... T.T
Anyways, u can give her something like a watch? Of course, the type which looks really nice, not too simple n not too heavy type. U can also give her some kinda stuff which u made personally. I think girls like it when someone makes something for them bc it shows how...what should I say? I was never in a relationship. So excuse my words. All I would suggest is something that u made for her.

Get something that's meaningful, like go to the place where you had your first date and or an inside joke related thing. On the Flash, Barry got Iris a replica of her mom's ring which she lost. Something like that, maybe??

Couple stuff? Date is a must

FLOWERS AND A GOOD DATE HOHO

Try giving her something related to what she loves. I mean, you are her boyfriend you are supposed to know what she loves and hates and all her little things. Get her something you know she'll absolutely love! ^^

Christmas letter is a must and u should give her flowers and maybe coo for her,
She'll love it:)

Honestly I think the best thing would be to take her out to a nice meal at a nice restaurant, or a day at the fair or something and just give her a great day/night ^^
Maybe if you can afford it, take her away on a holiday for a weekend or something, people normally (I dont speak for everyone) love when people make them feel special.

Cook for her and have a great Christmas night =)coz girl always wish for someone to cook for her esp from someone she loved =)

If you know how to play music then maybe you can write your own Xmas song , record it or better play it live for her ? If not you can write her poems ? Or maybe sew her a teddy bear something that you made yourself? Maybe baked her f. Cookie ?

A small and cute cosmetic bag. She will like it.

But in her case, I suggest you to give the simple but still looks cute. Better if you get a couple bracelets too...

Although she's not a fan of jewelry, basically girls don't like it either they prefer something simple such as handmade bracelet or because they are expensive. Try to give her one, because when a girl get something that she doesn't often get it but one day someone special gives her that, it would be her best treasure. ^__^ by the way, that's my opinion. Good luck boy!