I am 34 years old, my husband is 37.. we have an amazing 3 year old boy and generally we are all very content with our life and in love with each other as a family...

Im slowly getting the need to have another one... although I'm 100% content don't feel anything is missing, I would like to give my son a sibling. That is the reason mostly why I want another baby as much as to extend our family.

My husband doesn't feel the same... or he says NOT YET... mostly because we/he has some financial worry this year and next as he wants to pay off all his debt. Which is a very mature and wise thing to do but I feel my clock is ticking, and I am scared and don't wish to go through pregnancy and birth over the age of 35-36.

What should I do? Push him to understand how I feel about my clock ticking OR respect his mature reasoning and just go with it and wait till he is ready?

Difficult question.
He probably knows about the risks for older women giving birth, but do you know the family finances as well as he does?
I would say that the answer is going to pivot on the financial situation. Having a tough time this year could mean future tough years.
Sit down together for a good two hours and study your finances. Write down your expenses for the last 12 months by category (food, housing, etc) and add them. Major one time ones that can be considered as spread over years, like a new car, put a dot next to and then divide those by the number of years you would buy them again. Put an x next to ones you could have done without. If you are paying credit card interest, that absolutely has to be paid first. It's highway robbery.
Then see how all the totals compare to income.
Then see which ones you can eliminate even further!
Then talk about costs of another baby, and go over any insurance plan you have, and make a list of added expenses. Nothing frivolous like new clothes.
It could take more than 2 hours. It could take days.

We kind of did this already and prepared a spread sheet with our expenses - our monthly ones which are always going to be there and with the ones that HAVE to be paid as soon as... he calculated that by end of this year the majority will be paid off and next yr will follow suit by paying his mum off as she helped us by paying off his credit cards to avoid interest and they agreed on a monthly repayment and by end of 2014 all will cleared.

But for me to wait till then is quite long especially for my age.. if we start trying in 2015... we may not even fall pregnant... or if we do it may take longer then expected as I'm getting older..

What are the exact risks of giving birth over a certain age?

My mum was 38 when she had my baby brother and had a very complicated pregnancy and nearly lost him at birth :(

All of my friends around me, who shared the 1st pregnancy all together, have either given birth to 2nd baby, or pregnant... I'm not saying I'm a follower and do everything they do but I'm kind of feeling it.. esp when they all tell me.. 'come now.. what you waiting for'

:(

He needs to be willing to talk to his mother about postponing paying her back. If she says no, that's that.
The risks are based on statistics over thousands of women. That means there are no 'exact' risks. You just can't know where on the graph you will fall - if something has a 1 in 4 chance, you can't know if you will be that 1 or the other 3. Down's Syndrome is the big one. The others mostly have to do with problems during pregnancy and at birth. Google 'pregnancy risk over 35' for many. Here's one:
What are the risks of having a baby if I'm 35 or older? | BabyCenter

It does seem that each generation gets a bit healthier and better able to have babies later in life, and tests and treatments are better. But that's just in general, and there is a limit.

I forgot to mention, my mother was 37 when she gave birth to my brother... he is now a healthy 27 yr old man.. however she had a very bad pregnancy, her placenta started tearing during the 3rd - 4th month of pregnancy. She did smoke a few cigarettes during that time, but this was back in the 80's and her doctor never stopped her :/
At birth.. she had problems also, my brother was still born but they managed to resuscitate him and he was fine...
So it does haunt me, whether.. is it in my family?? Will history repeat itself??

My mums pregnancy with me on other hand was smooth, same as my 1st pregnancy.

I don't think you can consider your mother's history regarding her age (other traits, yes, genetic ones).
She smoked before pregnant regardless of during, I assume, and she was probably less healthy overall because of it.
The question is how healthy you are.
(PS: Stillborn is dead, not the same as not breathing for a brief time.)