Hi Sweetpea,
It's very hard not to worry about something like this, so I won't tell you to relax and not worry.
Please consider getting a second opinion. I understand the comfort level you have with your gyno, but it won't hurt to obtain the opinion of a second person. Depending upon your gyno's diagnosis, along with your age and family/personal medical history, she will hopefully recommend a mammogram. If she does recommend a mammogram, ask questions about the facility providing that service, especially about the type of mammography technique they will be using. Some use X-ray, and others will use MRI or sonogram. Some will use the squeeze-plate method, others will use the sonogram sensing tool (don't know the medical term for it). There are so many techniques with differing results, you could maybe do a bit of research ahead of time.
Because you have an autoimmune disease, it's very important you get thoroughly tested. Also, review what's been going on with your body the past month or so to see if your AUD has been flaring up - the breast lumpiness may be a reaction in the lymph glands. I also have an AUD, and I've noticed that my breasts react when I'm having a flare-up.
Ladies, when you check your breasts every month, include your underarms, too. The same rules apply (unusual lumps, swelling, discoloration, etc.) as for your breasts.