Hi there and welcome!
1. don't worry about DH and housemate right now. Changing your own diet is hard enough- if you stay the course and they see your results, maybe they will become curious/interested/motivated by you. But DON'T try to force it on them. Adults have to come to their decisions.
2. for your little one, why not strat replacing some of the unhealthy stuff with healthy stuff you go out of the way to make "fun" or appealing to a toddler? My mom did this when i got diabetes at age 8, and it ended up in me choosing a career in health and wellness.
I would google paleo kids or something to that effect.
A few ideas:
instead of baking cakespies- you could do baked apples, cored and stuffed with cinnamon, nuts/raisins. you could do a peach cobbler with a shredded coconut or almond flour topping.
instead of icecream what about a smoothie made with a frozen banana, nut butter and milk/milk alternative.
skewers of fruit and cheese makes it "fun"
apple slices and babycarrots dipped in nutbutter
i loved ants on a log, even as a very young kid- celery stuffe with pb and raisins
google south beach peanut butter cookies- they are cookies made just from pb, an egg, vanilla and sweetener
try making carrot "fries" or mashed cauli "fauxtatoes." zuchiini breaded in parmesan would be appealing, i think?
left over meatballs could be easy snack.
dehydrated fruit instead of cereal.....
for yougurt, i would just get the unsweetened kind and sweeten it yourself and add fresh fruit. you can even make easy syrup by heating berries of choice and a little sweetener until it is syrupy- strawberry and blueberries are my two favorites for this.
3. good luck TTC! don't worry about whether you can stay on plan during pregnancy, before you are pregnant. know that by losing weight and getting healthier now, it is more likely you will conceive. once ou become pregnant you will know a lot more the diet, and can decide how to adapt to fit the needs you will have during pregnancy.
There is also a subforum here for pregnant women/new moms if you scroll down a bit.