To ask for a second opinion?

[Boobyso]

I noticed a large lump/swelling under my left armpit around a week ago.

I had an appointment this morning and the doctor acknowledged there was swelling of some sort but told me it was probably just breast tissue and to keep an eye on it for a couple of weeks and if it changes then to go back to the doctor.

They also done a breast exam and couldn’t feel anything.

WIBU to ask for another opinion? Or am I being paranoid?

I would absolutely not touch it for a week, and then see how it is. Repeated touching/ feeling makes it swell. When are you due a period?

My period is due in just under 2 weeks so I have a while to wait.

you're right, I will just keep an eye on it

Doctor sounds totally reasonable, they listened to your concerns, examined you and came up with a reasonable plan, I would do as they suggested.