I work in a supermarket and tbh from your OP all of the individual things probably wouldn't bother people but all of them in together is probably just rubbing people up the wrong way as it comes off as very antisocial and standoffish.
You don't have to be the life and soul of the store but there is a middle ground between zero interaction and being involved in everything. You can be quiet without being rude, especially in retail where you're expected to be approachable to customers etc. You dont have to be BFFs with everyone you work with but you can be friendly and part of that is connecting with the people you work with rather than actively ignoring them.
1. I'm too quiet I don't join in conversations
When you say you don't join in is it that you don't join in general conversation or any conversation? Where I work there are often general conversations going on in the canteen that anyone can chip into and nobody would notice or be bothered if you didn't join in every single one but if you totally ignore everyone all of the time then that will be noticed. Equally if someone is trying to engage you in direct conversation and you are just ignoring them or shut them down every single time then that comes across as rude.
2. I haven't made an effort to join the facebook messenger /whatapp groups
Whilst FB/WhatsApp groups aren't compulsory, if your store/department has one why havent you joined? My department mostly uses ours to arrange shift swaps/ask for cover and arrange social events (eg, XYZ will be watching the England game at ABC bar on Wednesday of you want to join us; Bingo night on Friday, meet outside at 7pm; it's my birthday this week, if anyone fancies joining me for drinks I'll be at XYZ pub from 7pm on Sunday etc).
It's not really a chat group but pretty much the entire department is in it as its the easiest way to stay in contact with each other especially handy when you're desperate for a last minute shift swap and can get hold of everyone at once rather than having to beg everyone individually
3.I always leave work on time sometimes without saying goodbye to my colleagues (told him I have to collect DD from childminder so don't have time to wait for colleagues to finish serving customers to say goodbye).
This comes across as rude - surely you can spare 30 seconds to say goodbye and let your colleagues know you're leaving? I always make the effort to say bye to my colleagues firstly because it is courtesy and secondly so they know I have actually left (as opposed to gone on break/nipped to the loo/busy helping a customer etc). Even if they're chatting to a customer I have never had someone taking issue with me politely interrupting to say "Sorry to interrupt Sandra, its 2pm so I'm leaving now. My till's locked and I'll give the keys to John on the way out. See you next week"
4. I don't go to any social events they have (only Christmas party)
Again, not obligatory, but if you never go to any events then it will come across as antisocial, especially if everyone else meeting up regularly
5. I don't socialise at lunchtime I sit reading my book
Nothing wrong with reading a book but if everyone else is chatting around the tables and you're ignoring everyone at every break time then it can seem like you're actively blocking people out. You don't have to be bffs but an occasional chat about last nights Corrie over your sandwich wouldn't hurt.
6. I don't contribute to collections (leaving, birthday etc)
Again, totally optional but never being part of any collections adds to the pattern of behaviour (never contributing, never socialising etc) where you aren't making any effort to be part of the group and working in retail is all about give and take and working together.