I can really recommend acupuncture and herbs to get your body into balance.
I just had my second child last October at the age of 45. I saw an acupuncturist and herbalist for about a year before I got pregnant. I really noticed my cycle (and hormones) balancing out and just an overall benefit to my health. I was on some pretty intense herbal treatments for about 3 months, and I really noticed a difference afterward, but the subtle treatments really helped me as well.
I ate ice cream and carbs., but I cut back on processed foods as much as possible and ate as much fresh fruits and veggies as possible and tried to eat whole grains instead of highly processed grains. (I cut back on sugar, but I didn't cut it out completely).
I would suggest seeing an acupuncturist/herbalist that specializes in fertility. They can help select the herb/supplements that are right for YOU and the issues that you are having with fertility.
Also meditation and prayer helped me a lot. While the acupuncture herbs and healthy diet balance the body, meditation, yoga, prayer, and chi-Gong can balance the mind to help your fertility and overall health. You can find things on youtube and at the library so you don't have to spend a lot of money.
It can be overwhelming trying to figure out what supplements to take, what foods to eat, what foods not to eat, what things to do or not do while trying to get pregnant. Just do the things that feel right for you and make sense to you and try not to obsess to much about it. Keep faith that a higher power will guide you in making the right choices in your personal journey. Only do things, read things and listen to things that lift you up and make you feel youthful and vital. Send feelings of love and gratitude to your body for giving you your other children and believe that it can do it again. (I hope all this doesn't sound too hokey, but I really do believe it helps)
Book-The Infertility Cure by Radine Lewis
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All the best of luck! Let me know if I can pass along any other info!