I do not think what your partner wants is about you. He has children and has difficulties with having them, i.e., he's separated from their mother(s) which makes relationships, child care and engagement more complicated and harder.

I am a stepmother and my husband and I discussed having children and he said, "I don't particularly want them, been there/done that, but it is up to you". I decided not to have children because I wanted any children of mine to have an interested father too. While my husband is a good father to his children and I am sure he would have been to any we had together, I could see he was beyond that stage in his life and so I had to choose which I wanted most: children or my husband's and my marriage/relationship being something we both would enjoy. I wanted my husband to be happy, first; I knew I could be happy with/without children.

If you want children that badly, I think you should find a partner who wants them too? It is not a "fault" that your partner is in a different place regarding children than you are, he's not deliberately being "mean" or trying to manipulate you by not wanting children with you, it is just the way it is.