Saving is so hard

My baby has literally everything she needs for now, I'm 7 months and don't NEED anything else for her. But it's so hard to not buy baby stuff. Any advice? I'm 20 and pay my bills but with the extra money that I do have leftover it's hard to not spend it on her because I'm a FTM and just really excited. I really want to save up a good amount of money before she's here so I'm able to buy things for her as she NEEDS them, or incase of an emergency (single mom) so only one fund. I have a checking account that I deposit cash into. Buying baby stuff is just so tempting, but I realize I need to cut a lot of the baby shopping out and just really need help and advice lol.