you can still wait for another 1 or 2 years...i took a gap year after high school, and then i went to uni but then i found out that i was in the wrong course. i'm turning 21 this september and i'm starting uni now...so yes, it can wait. you can use this time to work part-time and decide if it's really psychology that you want to study. you'd have to dedicate all your time to uni and i'm not gonna lie, you won't be able to enjoy the whole experience with the baby, especially a new-born. so, my advice is, yes, just wait. however, i don't think you are really aware of how difficult giving birth and raising a baby is, since you are considering going to uni at the same time, which indicates immaturity. you will have endless doctor appointments, some days you won't even feel like leaving your bed, and when the baby is born you would have to be there for him/her all the time. young babies need attention, they wake you up at night, if they have a fever or so you have to run to the doctor, no matter what time. do you really think you could do well in an exam if you spend half of your night taking care of your baby? you might be able to get a degree, but you are going to work harder than most of us.
just think your decision through...are you REALLY prepared to take care of a baby? are you financially and emotionally prepared? are you willing to throw your youth in the rubbish and not have the experiences that university students should have? it's up to you.