Does every girl get a necklace with their sorority letters upon becoming a member?
 

because I thought just some people bigs bought necklaces for them as a gift, but I think pretty much everyone got one, but I didnt.
Should I have gotten one?

Some do.

I can't speak for other sororities, but in mine buying your little letters is mandatory, buying them a necklace is optional but a lot of people usually do. I think this also varies by chapter but I'm not totally sure. If you don't want to ask your big about it you could always ask your new member educator/pledge mom (idk what they are called in your sorority). But really I wouldn't worry about it too much. You're an active and that is exciting whether or not you have a necklace! :) If you really want one you could always buy one yourself or hint your to your parents for christmas haha

This is one of those things that breaks down to campus and even chapter culture. In order words, none of us can answer one way or the other.

Sometimes you get paired with a less than stellar big. I spent all of 15 minutes with mine on big reveal night and she gave me a crappy stuffed animal/monster thing that was neither our mascot nor our colors. Then she dropped me off at my dorm while all my pledge sisters went out with their bigs. I may have seen her at a couple of formal meetings in the years after. That was the extent of my relationship with my big. Perhaps yours dropped the ball. Don't let that interfere with your perception of your sorority. For a long time, I thought there was something wrong with me. Nope, she just shouldn't have taken a little. Ever.

If you have a good relationship with your big, then don't sweat it. Money may be tight for her right now or there may be another reason she hasn't gotten one for you yet.

You said that not EVERYone got a necklace, so it sounds like it is not a required gift in your chapter. There are a lot of possible reasons why you didn't get one and I do understand why you might be disappointed. Money might be really tight for her.

Assume the best of her and cut her some slack. You will be happier if you do.
Concentrate on developing a great relationship with your big and just buy one for yourself if you want one.

This is a reason a lot of chapters have moved to uniform gifts. However, gifts should not be used to measure worth of any relationship. Like another poster said, lavaliers are not that hard to come by and could be purchased as a holiday gift by your parents if you really need to have one. You shouldn't decide that your bid sis isn't as good as the others or she doesn't like you or wasn't as generous because you didn't get a necklace. You don't know her situation. Be grateful for everything she has done for you and don't focus on what you don't have.

Ding! ding! ding! We have a winner.

Yeah, my big deactivated like 2 months after my initiation. Everyone else got a lavaliere but me, :-/ It happens. Luckily my little is fabulous and got me one for my graduation.

Next year, when you get a little, buy yourself a necklace when you buy her one.

Why wait till next year? Find one online, send the link to your parents, and tell them you would love one for Christmas.

My parents were pretty anti-Greek (they paid for my sorority, so I was lucky, but they really, really didn't get it), so I always felt stupid asking for sorority stuff for Xmas.

Personally, I feel that buying one for yourself while you get one for a little would make it feel special and be something that I could "justify" if I needed to, but by all means, if your parents would get you one for Christmas or your birthday, that's an excellent option.