Hi there, It was really strange reading your post because I must admit that I felt exactly like that. I was 18 when I fell pregnant and my DP was 16. It was so hard. My ds is now 7 my partner and I are still together and are now almost due to have our 3rd baby. I know it is very hard at the time but you can move on. I still think ( sometimes) that I missed out on things but it has worked out for us.
The problem I had was that becauce I had this stigma attatched to me ( young mum) that I found it really hard to get older ( in my head ) so when I turned 25 it was really hard.
I was no longer looked at as a young mum and that was really weird. People are shocked when they find out how young we are because you do start to hang out with older friends, their kids are in the same age group and you have far more in common with them.
Good luck with raising Imogen it will be a hard but very rewarding road