Don't get into that mentality of likening kids to pets. Big, big difference! A puppy will not be there for you when you're on your death bed, a puppy is not a family legacy(the puppy will be carrying on the blood line of other dogs, your child will be from your bloodline), a puppy can not love you the way a human can.
Furthermore, puppies, dogs, any pets are as expensive, if not more than raising a child or caring for a human. There is definitely no affordable insurance for pet care, and if they should get sick it costs the same to treat a dog/pet as a human. Even palliative care (hospice/euthanasia/death) is outrageous for pets. Don't forget food, maintenance (vaccinations) and daycare (boarding) if you need to travel or go away for an extended amount of time. And dogs especially need constant human interaction, exercise and care....even after they're grown up. They can't do chores or help contribute to the household like an older child can. They do make a lot of mess with hair, poop, pee and vomit that only you can clean up. Even a well trained dog warrants getting a well made and expensive vaccum and shampooer to keep the house smelling and looking presentable. Don't even get me started about lawn care and having a supply of baggies and a scooper for daily walks to the park.
I say, put things in perspective. If you want a child, have one. There's nothing wrong with bunk beds if your home is small, and with creative budgeting a child doesn't have to be expensive. I think it's how you look at it. Children are work and cost money, but the rewards are boundless and there's a payoff in the end that goes well beyond warm licks from a creature who operates on only instinct versus reason, and with smelly breath to boot. :)
If the biological clock is ticking...listen. I have many friends in their early 40's who mistakenly believed they could have kids if they wanted to until they were in their mid-40's. Guess what. Only two of them have been able to do so. The others have resigned to the fact they will never have a child without adoption, and one other has gone into debt doing several rounds of IVF before she could have her baby. Don't wait. If you are blessed to have a child, everything else will work out.