Thank you both for your words of support and advice. I'm so thankful for this forum, I've learned so much from everyone here.
@ivfbeenbusy I'm definitely going to take your advice and have a break for a cycle. I definitely think my body needs a 'reset', not to mention I could do with a break from the stress of it. I'm 35, so I don't have time on my side. I turned 35 about 10 days after my first MC 
and have never felt so 'geriatric'. It's that horrible age that's always quoted when 'fertility drops', 'risk of miscarriage increases' etc etc...
I am incredibly lucky that I already have one DD (aged 2) who is of course my universe, and I thank my lucky stars for her every day. Part of my longing for a second is for her to have a sibling. I know lots of people struggle to have even one, so I know it might sound greedy. If she is my one and only, I will still be thankful every single day. But, I really hope we can complete our family with one more some day soon.
I'm going to ask to see the GP straight after Christmas - you're right I think it's important that I at least have it added to my notes that this has happened. Deep down I'm worried I might have a problem with my uterus lining not being thick enough. My periods have been ridiculously light for a while now, and even my miscarriage bleed was pretty light (at 6+4), so I'm going to raise that concern with her and see what she says.