You're not stupid! I bet every new mum wonders the same thing. I had exactly the same questions when I had my DD, and a helpful bit of advice I got from an ABA member was to try to make sure you drain each breast within a 24 hour period. Doesn't matter if its not at one feed / one sitting. Once (if?) your DD starts doing a cluster feeding session in the evenings, you might find that your BBs are getting pretty well drained and floppy by the end of each day And for lumps, yep, massage in the shower.
Congratulations xx