Very unexpected pregnancy!

My partner and I have been together just over two years. I’m 35 and she’s 37.
I’ve not had any long term relationships in my time, just dating and a few much shorter relationships.
My partner was previously in a 10+ year relationship and has a 7yr old son that I get along with really well! However our dynamic is still very independent and relates to when she has her son.
Two weeks ago she mentioned she is very likely pregnant! We have always used contraception but nonetheless here we are.
I have a tonne of faith in our relationship, but equally we’ve never even lived together and her son is also in the mix, so I want to do the right thing by them both!
We are in shreds over this, and torn between the head vs heart battles.
Any input would be so greatly appreciated! We just don’t know if we can go ahead with it yet or not.
We’re both very emotional people and feel deeply about the situation either way.
Appreciate you reading this and taking the time. Thank you!