As a 31 yr old father of a 2 yr old and another on the way. This is my advice.
The kid needs a Mom AND a Dad, together, in the same house. I think you should get married.
Your world now revolves around your child.
Not saying the kid runs the show but your decisions will all be impacted by the baby.
Get Used Clothes/toys/books/strollers/crib/etc from eBay/garage sales/thrift stores etc.
Buy diapers/wipes on sale, check slickdeals.net otherwise I have found aldi to be a decent value.
Breastfeeding is best, and free.
Once kid starts eating pureed/solids make your own.
Steam a sweet potato, carrot, apple etc and blend it up, put in ice cube trays, makes food for a week.
Once kid is 1 yr old they should eat what you eat, no cooking separate meals for the kid(this will probably make you eat more healthy food as well)
Be patient, and try to plan ahead, gone are the days of spending all day wrenching on your car. I can only work when the baby falls asleep.
Enjoy that baby, kids grow so fast and change so much, treasure your time with them.
I cannot imagine life without my sweet child.