Unbeliever you are going to be just fine whatever you choose to do. You are thinking clearly and obviously have considered everything. If you end up a single parent, don't be afraid. Just be very very careful not to have a second child while single, that gets harder to juggle. But one child is awesome to raise alone if it turns out that way. Women often end up doing 90% of everything anyway even if they are married.
You are going to be a bit more emotional while pregnant as your hormones change. If you feel like you are being pressured, take a step back. This is a time you need to enjoy and stay calm. It does effect the baby if mom is stressed. Personally, if your pregnancy is going very well, I being an adventurer would head over there for the experience while on your leave. I have travelled quite a bit and do not regret any of it.
{{{{{{{{Unbeliever}}}}}}}}} Enjoy the new life growing inside you. Don't be pressured. YOU have everything to lose, he has little to lose. That is just the way it works out.