Hi jc!
My wife and I are trying to have another child also. We have a 16 month son. With our first child it took us 2 years before she got pregnant. My wife and I are overweight with my wife heavier than myself. I gained some sympathy weight with my wife since the birth of my son.
One thing my wife and I did the year david was conceived, we decided to run the rock and roll half marathon in virginia beach, va labor day weekend. This was my wife's idea and she never ran in her life. (i have run almost all my life.) she did lose about 20 lbs during training. She also has a problem with an irregular cycle (every 2-3 months she will have her period). Less than 4 months later, we found out she was pregnant. She found out two days before christmas and told me christmas morning.
We both were tested to see if there were other issues. I was tested 1st because it is easier to test men on their sperm count which they said I was fine. My wifes test were inconclusive. Generally both your husband should get tested for sperm count and you should be tested for ovulation. It wouldn't hurt to attempt to try to lose weight and exercise (both you and your husband). I am not a medical professional but you almost need to find what works for you.
If you are 35, you are considered as a high risk pregnancy until the doctor rules it out by how your pregnancy progresses.
I wish you and your husband luck with your third child jc. If you can add anything to our situation and give wisdom please do!
Many blessings
tom z