Lisa I feel very much the same about mine. In both cases I had less than a week of being pregnant before spotting and knowing it was over. I feel like that was easier (for me) because I hadn't even had time to get used to the idea so it just felt like oh, I'm not pregnant any more than an actual loss. I think I'd struggle if we'd already started to plan and get properly excited though I know that DH did already get excited and took it quite hard - harder than me, unusually, I think.
I think it was also easier for me because I know our chances of miscarriage are higher so I was half expecting it? It must be horrible to be totally innocent about the possibility and then just have it happen out of the blue. My main emotion about this whole thing is frustration and annoyance that it's taking a long time.
On that note I am spotting so looks like AF is on its way, sigh.
Orange DTD every day he's there should be fine if it's about the right time. If he can't change when he goes then it wouldn't do you any good to know for certain anyway would it? The fertile period is more than 3 days meaning you're almost certainly catching it, and I reckon you'd be really unlucky to have his 3 days fall exactly on the 3 most important days anyway, so I wouldn't worry.
Timing isn't usually the issue, it's most commonly egg or sperm quality. The ladies earlier were talking about the book It Starts With The Egg which I haven't read but sounds like a good read for improving egg quality, I bet there is stuff to read about sperm too - but a sperm analysis is fairly easy to get done I think if you want a definite answer.
Fertility lube - much better than standard lube and so if you're normally lube users it's worth trying. If you don't normally use/need lube then it doesn't confer any advantages. But yes don't use standard stuff as it tends to have spermicide in it! 
You only have about a 20-25% chance of conception each cycle, even with perfectly timed sex and everything lined up so it's okay if you're waiting a few cycles but there's no harm in asking your GP after how long they'll refer you for testing if you're worried about your age. Did I read right that you've had 3 MC in a row - is that not enough to be referred for recurrent miscarriage? Or does it "reset" if you've had a live birth? Should be worth asking about referrals anyway as 4x MC plus a pregnancy with abnormalities is a worrying enough pattern - just see whether they would investigate, I suppose.