Breast Clinic Tomorrow for Lump under armpit

Hi 

Just joined here tonight. I'm sitting getting really worked up. Have an emergency breast clinic appointment tomorrow for a swelling with a mass of some sort under my armpit. 

I an a very anxious person too so I talk myself down from thinking I have something wrong. Iv known about this for a couple of months but kept telling myself I was being over anxious. Now I'm terrified iv waited too long. I have convinced myself im riddled with cancer because my abdomen has been distended for many months now and really awful periods. And for a couple weeks iv had a swelling below my knee and the bone of that leg has had so much pain. Iv now managed to convince myself that tomorrow they wont find the cancer that's running all round my body affecting my womb, my lymph system and my bones. I know this is ridiculous but because of all the issues, if nothing is found tomorrow I wont believe them. Is that a ridiculous way to think? And do I even mention these other things or not? It is the breast clinic not the gynae and leg clinic but what if it's all connected. But then if I do say anything they might put me into a psychiatric ward!!! Sorry I'm just ranting on with fear and worry about tomorrow. 

Thank you if you read this. X