Scared to get sick

I'm not scare to take pills or go thru a long wait to see the doctor.
I just feel like I can't get sick. Because once I do, that's when things start acting up in the house.
My dad would be even MORE caring ( I don't mind) but its just that it makes me uncomfortable knowing that my stepmom is around. Because I feel like her glare is gonna burn a hole thru my dad's head. On the second day of me getting sick after my dad left for work she says "sigh, seriously, different people born at different times" (trying to translate what ever she said from cantonese). So yeah..like she already told me how she feels about my dad's treatment toward me in comparison to her or my little brother. Its just that when my little sister and I get sick, she barely ask how we're doing, or make things especially for us. Like I didn't feel like eating for two days in a row, dad made me pumpkin congee. My stepmom would have never done it for me. Or feel my head to make sure I didn't get a fever, like my dad does every morning. Its just different. I don't know...my bro got my mom to pamper over him, so I don't know why does she want both her and my dad to like watch over him. I mean for god sake I watch over my little brother, always constantly asking him how he's doing. So whats the big deal. Maybe my dad is just too use to one side parenting. I don't know. It just feels so awkward that I know how my stepmom feels and don't know how to handle the situation. Even my dad knows that my stepmom is jealous. So how come he's not doing anything? Like everyone knows what each other is thinking, yet nothing is done to solve it.

I'm running out of ideas and strength to continue holding the family together. Its too much for a 20 year old to do it. I already feel like 30.