Welcome to the forum. I am sorry to hear you are struggling with so many different things. There is a lot of stress in moving (three times in a year), adjusting to life without your pop, changing schools and having to go through being bullied. All these things on top of each other sounds really really stressful. Be kind to yourself during this difficult time.
It is great that you are back with your mum and are able to make plans with people despite finding this stressful. It can take time and a lot of effort to find a good support network and establish friends. I know from my own experience of moving from one side of the country to the other to a small town that it took quite a while to really feel connected to my new home. So much adjusting and not feeling settled and supported can be hard and I wonder if you have thought about talking with someone like a counsellor or your mum about things?
Having grief around losing your pop may also be something you could talk about. Grief is a process that can take a long time for some people. Talking about your feelings of loss can often help you start to feel better. I will suggest a few options of where you might find support.
There is a program online that some people find helpful called eheadspace. You can chat with counsellors online or over the phone and it is specific to young people. You can have a look at this by going to this website. https://headspace.org.au/eheadspace/
Another option might be to talk to your school counsellor about how you're finding it tough to adjust since your pop has passed and you could also ask for some help in finding other ways to connect with people. Often there are community groups where you might find like minded people but this would depend on where you live.
Having worry around not having friends you can count on is a common experience and getting some support around this worry could be a great start to feeling more confident and positive. There is help and support out there but sometimes it can take a bit of work to find it. You have already reached out on the beyondblue forum but if it does not give you enough support, then please continue to reach out to other supports around you.
If you are ever really struggling and want to talk on the phone to someone, the KidsHelpLine on 1800 55 1800 is service that is available to you for free 24/7.
Wishing you the best possible outcome,