I've found a lump

So I'm freaking out a bit probably unnecessarily but I can't help it. I found a lump a couple of weeks ago- it's tiny but easy to feel- it's just behind my nipple. I've seen the GP who examined me and has sent an urgent referral for the breast clinic a week ago- just waiting for the appointment to come through to hopefully get some answers. I'm not entirely sure what to expect from the appointment when it come through, and I guess I'm just posting here to hear others people's experiences and if anyone has any advice while I wait?