Nic ,
so sorry to hear about your miscarrage, I have had 2 myself and its a very hard thing to deal with. I had a terrible time conceiveing my first 2 ( hence 6 1/2 yr gap between the first 2!!) but now I have 3 lovely boys, 20, 13 and 10, so never give up. I never forget the pain though, like when friends tell you they are pregnant and you want to be pleased for them and you are, but also it cuts you really deep, so I do understand.
i wopuld think that this will pay a major part in the non moving scales, your body had been through a real roller coaster ride and will need sometime to recover, I take my hat off to you for being so positive about carrying on with your weightloss journey, you are coping well, I hope that things settle for you soon and you get to your target, both weightwise and babywise.
i wouldnt worry aboput the tuna and milk, you are still having a low cal diet and am sure your efforts will be rewarded soon.