Great news, @LouiseR, all round. I hope that fluid buildup settles so you can start getting some quality sleep again, soon, in your preferred position! I was really surprised that my own 'wound' wasn't as confronting as I thought it would be (as he had to remove my nipple & sew it back on again ....) so don't be too scared to have a peek!! I had one stitch that didn't dissolve too & it was sticking out & just needed the nurse to pull it out - so you maybe should be aware of how it looks 'now' vs in a week or so .....
Have you been assigned a Breast Care nurse yet? If not, go onto the Mcgrath website & check who is available in your area. You can liaise with her re the fluid buildup & may even accompany you to meetings, if you need 'support' ... they cover 'all cancers' now, so you'll just need to add 'BC' .. and your post code! ;)
https://www.mcgrathfoundation.com.au/get-support/find-a-nurse/take care & all the best as you continue healing.