Babies are such hard work, more work than you think. They need your constant attention.
Also, the baby will only be a cute baby for a year. Then you'll have an annoying 6/7/8 year old you have to deal with. Take to school and back every day, find childcare for in all the school holidays.
The baby will not make your mental health better, I can say that for sure. It will do the opposite. Having a baby can be really isolating, especially when you are so young. Your friends will quickly disappear once the baby is born. Even mothers in their 30's who have everything sorted practically, struggle with their mental health after having a baby.
Where will you live long term? How will you work and afford childcare? Do you know how much rent is for a 2 bed flat in your area? Do you know how much a day nursery costs for a full time place? You don't yet have many qualifications so how will you get a job to afford all this? You can't get a job without childcare. It's not ok to expect your mum to do all of this. You'll be ruining her life.
So many questions.
You aren't in a good place to have a baby. You have poor mental health, you have no money, you live with your parents, you don't have any qualifications and you don't have a well paying job. You don't have a supportive partner.
You're actually ruining your own life. How much easier would all this be if you could just crack on, get your qualifications, get a job, meet someone, buy a house, then have a baby when you're both happy, stable and can afford it.
I wouldn't bring a baby into this situation. For the baby, and for you.