The reason you don't want to give up the baby is because he was created by you and someone you love. You know that you CAN'T raise the baby. You admitted to not being mature enough. You're also depressed, I can tell because I've been there too. You cannot raise a baby in that state. Sometimes females have a baby and either become very depressed or sometimes don't care at all for the child. I know it's hard to imagine, but it has to do with the hormones.
You have three options: 1) Abortion, 2) Keeping the baby, or 3) placing him up for adoption.
Trust me, I know how hard it is, but you know you cannot raise the baby yourself. You're seventeen, and while your family and his are supportive, there are so many more things you are not taking into consideration. Financial aid, for example. You will have to drop out of school to raise the child. You will not be able to go to college right away if at all, etc.
Do not feel bad, for this is your life. If you cannot take care of the child, it would be better to not put him through it. However, adoption is still an option to consider. Though, many mothers go through the pregnancy and it is hard to put the child up for adoption after he is born.
I'd say, talk to Tyler. You and him will know the best thing to do.
P.S I just reread the last part of your question. It seems like you actually have it all figured out. It might not be so hard after all. However, you would need more that 8 weeks off. The baby would only be 8 weeks, would you feel secure placing that baby in a daycare at 8 weeks? And also, most parents who have children at young ages, don't stay together as they age. Just something to be weary of.