It isn't so much "missing my youth" that gets me, but rather all the external factors that come with being a young and unprepared parent.
1. The Odds of Your Relationship Lasting are Against You
Nobody sets out to be a single mother, but picking a life partner when you don't even quite know who you are is a surefire way to become one. A majority of teen pregnancy cases aren't planned or expected; therefore two young people who still have a lot of life to live find it much more difficult to commit to each other when life actually starts for them. You may realize later that you don't want the same things in life, and as you grow and discover more of who you are, you grow farther away from them. Even if this turns out to be your life partner, taking time to establish yourselves and have individual experiences before having children is very important.
2. The Single-Mother Stigma is Very Much a Thing
Sadly enough, society still treats single mothers like "damaged goods" - which is quite aggravating because a lump sum of us made the decision to leave the relationship, not the other way around. When it comes to dating, having children is a huge factor - understandably; but although there are men who don't mind and absolutely love kids, there are also men who believe dating a single mother is a liability. Ladies, while he is entitled to his preference with no apologies, we certainly don't have the time for that!
3. Reaching Financial Stability is Significantly Harder
Childcare is one of the most expensive things about having children. Every other youth has the luxury of getting up and going as they please. They can complete a degree or certify in a trade - while keeping a full time job to sustain just themselves, as well as a social life to balance their sanity. Doing all of this with children requires a lot of support from family and/or friends. This means having someone who is trusted and willing to care for your child(ren) - either free or for a substantially low fee - while you work and/or obtain an education. Without this kind of support, many single mothers find themselves trapped in that cycle of "I wanna earn a better living but I need a sitter, to afford a sitter I'd need a well-paying career, to get a well-paying career I'd need to further my education or skill set, but to do that I'd need a sitter". The good news is that there is a way out no matter what your circumstances are, there are always resources; however, it is undoubtedly better to earn a decent income and become comfortable in your finances before taking on a responsibility as big as a child.
4. The Broken Family Feeling is Real
Holidays hit a little harder but you do get through it. The guilt in your heart that your children are missing something when they see "whole" families; but perhaps they don't feel this way, it's all in our own head. Either way, that feeling is quite depressing, and it will come around every holiday season until you are at peace with your reality. Find peace with your reality.
5. Scheduling Time With Each Parent Can Be Stressful
Especially at the beginning of the split-up, when both parties are mentally and physically readjusting to their new lives. Who gets the kids on Christmas, Thanksgiving, after school on Friday, etc. If you're lucky, you can both agree on a routine off the get go. If you're even luckier, neither of you deal with the other wielding the child as a control mechanism for the other. In break-ups where one party is completely bitter over it, you may deal with very ugly custody and child support battles. There's also the jealous rage, where the bitter party does everything in their power to sabotage your new relationship, using the child(ren) to do it. You don't have to deal with break-up pains if you have children with someone you're truly happy with, even on days you wanna stab them.
6. You May Miss Some Milestones You Can't Get Back
In my personal case, having a child roughly a year after high school, I was obviously not prepared in anyway. I was practically a child myself, I didn't make a decent income and I didn't even live on my own yet. I would've loved to do a maternity photo shoot, I would've loved a baby shower - perhaps gender reveal, I would've loved better newborn photography... these were all things I could neither afford, nor was I even mature enough to realize I'd miss these fleeting moments. Becoming a parent at a young age fast-tracks you into adulthood and forces you to act at a higher level of maturity than most your age. Not every case is the same, of course, there are teen parents who were perfectly prepared and didn't miss a single milestone.
Ultimately, we all want to find our own individual happiness. While it may be okay to take hasty risks with someone you feel deeply connected to, placing a child in that mix should be a long, thought-out, and discussed decision. Financial stability is 100% necessary and I believe, based on my experience, two people should be absolutely sure of each other, at least in that moment, before they procreate.
It's not all rainy days though, having children young has quite a few perks of it's own. Being a young parent has its good and bad days. Read about "8 Perks of Having Children Very Young."