I found a lump months ago - stressed about going to doctors

So I'd say its been about half a year since I found it. Im only 18. When I first noticed, I went to the GP and they told me its probably a cyst and nothing to worry about, but to come back if it didn't go away. I never went back. I now go to a different GP, so I'm going to make an appointment there. I'm just very worried. I feel like if it is something bad (as the more I google the less it sounds like a cyst), I will absolutely blame myself for not going sooner. I was stupid, really. Acting as if me ignoring it will make it go away. I've not found anything online about the location of this lump - its like right by the nipple. I'm going to try and book an appointment for tomorrow, but I'm just so worried. All they'll do is a physical examination, and then I'll likely need to wait up to 6 weeks for an ultrasound. I wish I could just the the ultrasound without the physical examination.