Concerned About Swollen Lymph Node in Left Armpit

Hey, I am a 22 year old female and I recently went to the breast dr for the 1st time since my OBGYN noticed a lump in my breasts. My breasts are fine, just pretty dense tissue and lumps that are not cancerous, but he did see one swollen lymph node in my left armpit. After he said that I got pretty anxious and scared. He said it could be from shaving or anything but idk. He did recommend I get genetic testing done since idk my biological dad’s medical history. But I think doing that will give me more anxiety. I go for a follow up to see if it’s changed in July. I feel like that’s too long to wait🤦🏼‍♀️ I don’t see or feel it tho but it does sometimes hurt in my armpit (not sure where the lymph node is located). Any ideas of what it could be? I am having pain in breasts but they gave me a sheet that tells me possible reasons why and what to do about it.