That's pretty much it. My DH's first wife died when my DSS was 3 (he's now 7). When we got married I felt a bit 'second wifey) but that has mainly disappeared now and only rarely comes back to me (often when I'm tired and feeling low). I think what helped was him saying that he felt differently about me and we had a deeper and more equal love (cheesy yes).
We want more children but I'm already worried about feeling like a 'second' again. He's already done all of the excitement, stress, tiredness etc of having a baby, I haven't. I also know my MIL will constantly say 'when DSS was a baby, his mother did this when he wouldn't do X'. If you see what I mean.
I want children with my DH, my DSS desperately wants a baby brother or sister but, I don't want to spend the whole time feeling like he's done it before.
I think part of the issue is feeling like nothing we do will be a first for my DH. I know it's my issue and I know I have to deal with it, but so far the only way is ignoring it which I don't think is particularly healthy!
Any advice/experience please?