What the others have said, basically.
'He said we had agreed that now wasn't the right time for a baby, and listed off all the reasons why we should terminate and try again in six months or so time. '
A termination is a big thing to go through for the sake of 6 months.
'He also said he knows how hard the decision is, it is entirely up to me and will support regardless. (...) I don't want my DH to resent me or a baby that he is adamant we are not ready for.'
He's said he will support you whatever you decide. If he thinks you'd be ready in 6 months, then you're not far off ready now.
The other thing to bear in mind of course is that regardless of age, TTC doesn't always pan out as we expect. You have a chance now, it can't be taken for granted. Sorry if that's a random and slightly morbid point. What if you had an abortion and then happened never to get pregnant again?
'I don't know what to do. Am I being selfish not having a termination at 14+ weeks because I think it would be too hard phisically and emotionally?'
No. You have to look after yourself, especially as you sound vulnerable maybe? I agree with previous posters - go to your GP (or go back, if you've been before) and explain to them how you're feeling. You could also try therapy etc. Even if you've tried lots of things, there's almost always more to try!
It's not selfish to think of your mental health- if you get ill then it will effect everyone close to you, so by looking after your health you are thinking of them.
Hugs xxxxx
'I'm shocked at all the self-declared pro-choice posters here judging OP for talking about having an abortion and TTC again in 6 months.
You aren't pro-choice if you make a moral judgement on another woman's choice to abort. '
I don't think we're making a moral judgement as such- OP asked our advice and we're just giving her our (asked for) opinions, that if she wants a baby in general and soon (which she presumably does as she's mentioned DH saying they should try in 6 months) then 6 months isn't long and not worth going through an abortion and then TTC again if it can be avoided.
No-one who's pro-choice would berate the OP for having an abortion she chose- but she's conflicted about it, that's why she asked our advice.
I saw another thread or two where posters were being pressured into having an abortion- it seems to be a thing nowadays. Women who are pro-choice would/should also be pro- a woman choosing to have a baby if she wants it. Being forced/pressured into an abortion is anti-choice.