Oh mamabear8 I’m sorry you’re feeling like this. Firstly try to slow down your thoughts. It really is a rollercoaster of emotions waiting to know.
You are being referred and will know more when you go to clinic. It’s an awful and anxious time.
I have had hard lumps that have turned out to be cysts which they can drain. Raised glands in your armpit can be lymph nodes struggling to fight a virus. As you say you’ve been suffering chronic fatigue. That in itself (as well as being mamabear to 8 wonderful children on your own) is a huge strain on your body and mind. You are amazing! 
you have done the right thing going to your go and getting a 2 week referral. 
Please know that you aren’t alone, this forum is great for a chat/get support./advice. Until you know facts try to slow down your thinking.  You can deal with what you know, when you know. Sending strength x

A mother of 8 kids, no wonder you're tired. I'd be laid out in bed, looking after just 2.

Brest cancer doesn't tend to cause fatigue. Not saying it can't, but doesn't tend to. Before my wife was diagnosed she had bad fatigue, she had a really sore back, with pains down her legs and a ****ty cough that i had been nagging her for months to go and see about. I won't lie, when she got her cancer diagnosis, and before body scans, i was fearing the worst. Her sore back turned out to be mechanical, her cough was allergies and her fatigue was most probably caused by stress (her mum and dad were elderly and they were in and out of hospital). Her mum eventually passed away. This is what her fatigue was put down to.

The oncologist said what i said about a 3cm (she had a 5cm and 2.5com one, with 2 lymphs involved) breast lump wouldn't cause fatigue. It's so easy before you have any facts at hand to lump everything together. It's what we as humans do. You have a lump, so ALL your symptoms must be derived from that. In reality, the human body is complex and can and usually does have more than 1 thing going on at the same time.

My rational brain agrees with you 100% I know I’m panicking way too soon into this but my adhd brain is losing the plot and I bet it’s the panic that’s causing the shoulder pain as it was its worst ever last night, my shoulders and across the top of my back feel like I have done a huge upper body work out in the gym. Ended up taking painkillers just to try and get some sleep and I have never had that before. But it’s probably stress because it only started a few days ago but is getting worse every day but I found the lump and the aching under my armpits started 2 weeks ago. Need to try and distract myself x

Your shoulders are a common place to hold stress  and you have the weight of the world on them at the moment.  I get pain in the muscles by my shoulder blades that goes right up my neck and gives my awful headaches.  Try to be aware of your posture, do shoulder rolls, lift them then let them fall lower.  Another one is to sit upright and look ahead. Gently extend your chin forward a few cm's then back.

Try to relax (which at the moment is like saying build a wall with water).  Heat wrap can also help or gentle massage of the area. 

Hope it helps x

Thankyou x