Is he moving away to uni, Joanna or going to a local university?
Do you live together? How does he feel about you having a child together?
Sorry for all the questions!
In theory, you have plenty of time to have more children if you're 27.
If he's the right man for you, maybe it's worth waiting till you're financially more secure.
A friend of mine got pregnant just before her DH started studying for a PGCE. Even though his course was only for a year, they found the drop in income really tough, and she was working full time, so they still had one good wage coming in.
I can relate to how you're feeling, I was desperately broody from when my DC1 was about 2 years old. I started my degree when she started full time school, and had my DC2 at the end of it, although I swapped courses so it took me 4 years to get my degree.
I know the feeling can be overwhelming. Don't know if you're aware of the one-child families thread on here. There are lots of people on there who only ever wanted one child, but also people who have one and really want another.