My comment is based on concern for you as some advice coming through is from Diep flap surgery not mastectomy with expanders. Totally different procedures.
Catheter is dependent on how your body reacts.
Drains, everyone is different, some are a few days some are much longer!
Hopefully this information helps you however, my concern was and still is, you're putting yourself in an anxious state of expectation and if your drains and bandages or lack thereof could do your head in thinking you've been ripped off after your fact finding information. The team looking after you will be able to answer your questions.
Take care