Hi Gamble,
I'm new to the forum but thought I'd post a reply to your post. It sounds like you've had a bit of a shock when you went to your GP, but she's clearly a good GP if she found another lump, so you should be able to take your concerns back to her if you're feeling very worried - hugs from me though!
An urgent referral means you should be seen by a specialist clinic within two weeks from when your doctor referred you, so I hope your appointment is very soon as the wait can be agonising. At the appointment they'll examine you again and do either an ultrasound scan or a mammogram, and they might want to take a sample from the lump too. Often times you will have a fair idea from the clinic what you should expect from your results, but waiting for the results can be really nerve wracking.
Try to look for the positives at the moment as there's a chance your GP is wrong and you may have a benign condition. I think there are some pages on this site dedicated to younger ladies like yourself who have children to think of, so they might be helpful if you haven't looked there yet?
Best of luck for your appointment though, I'm hoping things will work out fine for you 🌻
C x