Your dream is your anxiety expressing itself - it means nothing wrt the actual chances of your pregnancy - congratulations on that btw 
I had 3 MCs before DS1 'stuck', then DS2, another MC and a further 2 DSs.
Every pregnancy loss is very upsetting, of course, but you do sound anxious.
Address your anxiety now, before you have a baby, because, trust me, looking after a newborn/baby/toddler/child/teenager is absofrickinglutely terrifying
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There is some evidence that reassurance scans are helpful - so go for one if you want. The problem is that no statistic in the world can tell you what you really want to know: will your pregnancy continue? So from that point of view, yes, it is a waiting game.
Wrt train journey/hen weekend: medically speaking, of course you can go. Only you can decide whether you are comfortable going.
It helped me to remind myself that women all over the world are pregnant and have babies under the most gawd-awful circumstances, so my normal activities are nothing compared to war zones and refugee camps
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IME conception/pregnancy etc are a total lottery and it is most helpful to really practice staying in the moment (look at Mindfulness techniques), enjoy the good bits and don't worry about the bad bits until they actually happen 