K.L.
Having lost 3 of my 4 pregnancies, I completely understand your hesitation as well as your desire to try for more. However, my last 2 were tubal pregnancies and my tubes had to be surgically removed, so I was never faced with the option of trying again after that. I cannot say what I would do in your circumstance, but I can tell you two things that might have helped me to make such a decision. One is spiritual and the other practical.
First, I've learned to trust every decision to prayer. It took me a while to learn how to observe the guidance prayer and meditation afforded me. I like a phrase my friend uses. She says that prayer works much better if you pray until your finished. I learned to pour my heart out in prayer and then put myself and everything I know into a state of acceptance for whatever guidance, support, comfort, protection, affection, or challenge may come. Once I understood that God's story is always a love story and trusted that completely, it became easy to sense the guidance that was given.
The practical information I can offer is in regard to gestational diabetes. There is a book by Dr. Peter D'Adamo, Live Right 4 Your Type, that may help you to overcome your vulnerability to that condition. Learning to eat the foods you are able to metabolize for the most benefit to your body and to avoid the foods that create metabolic challenges for you can work like magic. They have proven that this diet actually resolves diabetic tendencies. The book also explains the type of exercise that is best for your blood type. So, if you knew that you could adapt your diet and exercise to be less vulnerable to gestation diabetes, you might have a much better chance for a successful pregnancy.
Either way, my heart is with you. My son is now 23 and we continue to be deeply grateful for the gift he is to our lives. But,I also know that, although we have only one child to share this life with us, we have 4 that we will know forever. I also know that I have shed more tears over the child we raised than over the children we lost. It may seem odd, but there is some amount of comfort in knowing that those children are safe. No one will ever crush their enthusiasm, try to abduct them, or betray their trust.
There is no right or wrong to these decisions. Love has never steered me wrong. But, sometimes Love says, "Take the risk." And, sometimes Love says, "You've done enough. Celebrate it." Perhaps Love is saying, "Just wait, for now." No one else can hear what Love is whispering into your heart. What often happens is that our heart, in these circumstances, is still screaming and full of agony. It always took me a couple of months for my heart to stop throbbing in grief and wanting to scream a scream that would echo through the heavens and rattle the stars. It can be difficult to hear what Love whispers in your heart while your heart is screaming. So, it might be helpful to let yourself have a few months of indecision about the future and let yourself move through this time of extraordinary pain before making a decision. Or, make the decision you need to make for now and know that you can revisit the question in a few months. Give yourself and your family what you need for now. It is enough, for now.