Relationship Advice HELP

I'm 18 & have a 7 month old son , his father isn't in his life and now I have a boyfriend who is 16 (17 in December ) we are gonna start ttc in October when I get off depo . We haven't had any problems so far and he loves my son and is great to him . Any advice on how to get pregnant quickly and how to keep this great relationship going ? TIA