Any advice?

I have an 8yr old and a 5 year old from a previous marriage. My fiance and I have been trying to conceive for about 10 months now with no luck. Thought we were a few times but got a negative 😔 With my daughter I was negative until I was 8 weeks preggo. Any advice on how to increase my chances? My fiance loves kids and has none so I would love to be able to give him one and complete our family. He is 34. I am 29. Both in good health. Thank you!