Adding to the family.

I would like to have another child in the future and so do my boyfriend, which he is willing to wait.  My son has had sibling fever for 3 years now.  First, he wanted a brother.  Then brother or sister. We got our now 2 year old cat, and that eased the heat.  Now he wants a brother and have came up with names!

I'm so nervous to be honest.  My son was unplanned and I was 15, frowned upon.  I feel there will never be a "good" time to try.  I'm so adiment about finances and future building and planning and security.  I'm in a custody battle right now even, my mother took my son and that's a mess in itself with lawyers and her keeping him away the best she can, she has wanted him since I found out I was pregnant (I still have legal custody and should have him within a year; I lost my home last year) if I were to conceive and he isn't in my home other than seeing his father I don't think I could feel happy, actually feel guilt.  Is it ok to add to my family if I'm still fighting for physical custody?  Does that make me non-loving?  I am fighting tooth and nail and will never give up.  And I'm nervous that I would feel guilt for enjoying not being "a shame" for not being a teen anymore.

I wanted my kids close in age, but always looked out for what's best for my son and our future.  Are there any mothers whom children have a gap and still great relationship?

Any feedback is awesome.