Trying to conceive

My partner and I have been together for just over a year. He already has a child from a previous relationship who I adore but we want to make our family complete by adding 1 more. It's been 3 months since we have been trying but nothing. I have had a miscarriage with a previous partner (I got pregnant the 1st time we slept together  so I know I can get pregnant) I'm just worried it's taking months to happen this time. Any advise?