[SUadpi]

I know exactly how you feel, as I was in your situation three years ago. I have always been on the shy side, but I was able to overcome it during recruitment (mostly because I knew I had no chance if I didn't put myself out there and try to be as upbeat and outgoing as possible). However, once I joined, it was really hard for me to get out of my comfort zone and initiate conversations with my new sisters. I felt like it came naturally to everyone else, and even though I was very excited about my sorority, it was hard for me to really put myself out there. I remember, like you, feeling like everyone else was instantly really close and that they would be weirded out if I tried to join them in conversations/outings etc.
But, when I started thinking about it, I realized that these women WANTED ME. They obviously liked me, or I wouldn't have been there in the first place. Once I came to grips with this, I decided to throw caution to the wind and made the effort to volunteer for specific things, asked sisters to join me for coffee/lunch/a movie/studying etc, and tried to start a conversation with at least one sister I'd never talked to before at each meeting/social/philanthropy event etc.Before long, I had great friends in not only my pledge class, but in each of the other pledge classes as well, and today, I can't believe that I ever felt uncomfortable around these women- they have become not only my sisters, but my life long best friends/confidantes/cheerleaders.
The funny thing is, once I finally started feeling comfortable and like I fit in, I learned that many of my sisters had felt the same way I did at first- a bit like a fish out of water- so it was something we all experienced and overcame together. You would be surprised at how many of your sisters are feeling/felt the same way. I'm sure they would love to get to know you better; after all, you'd wouldn't have gotten a bid if the sisters didn't think you'd fit in with the chapter. Although it may be awkward at first, make the effort to initiate conversations with your sisters (try to talk to at least one different sister each time you're all together- she will likely be pleasantly surprised and can help you connect to other sisters), attend both mandatory and non mandatory events (so you are included in/ a part of the "fun" stuff as well), and think about ways that you can contribute to the chapter through volunteering your talents/skills in various areas.
Work week is a GREAT opportunity to bond with your sisters, as everyone is working hard for a common cause, and the long hours, sleep deprivation, and at times extremely emotional situations can really bring a chapter together. If the opportunity arises, ask if you can tag along the next time your sisters run an errand/grab some food/go for coffee or ice cream etc. I promise they will gladly include you, and they will not just "tolerate" your presence; they are your sisters and will be happy you wanted to join them!
It can be difficult sometimes, but I promise, if you make the effort, it will be sooooo worth it!! You have nothing to lose and everything to gain- lifelong close friendships with your sisters! Good luck!