IM GETTING SO IMPATIENT!

I'm going to try to make this short. I have a 16 month old whom I love to death and so blessed for. But when I was looking through his baby pics, my heart sunk. I miss having a new born. My husband and I talked and were going to try for our second after he starts his new job (couple months after). I was fine with that, but then his brother got engaged and he said after their wedding. THE WEDDING ISNT UNTIL DEC OR NOV or NEXT YEAR! Idk they keep changing it. Obviously I dont want that because as petty as it sounds, I dont want to be pregnant with his brothers wife. (She has told me how shes going to get pregnant right after they are married) I hate her! All we've done is bump heads. She treats my son like hes hers, she buys him things i said I would(i stopped telling her what I was buying him but she still finds out), she forces my son to hug her, she grabs him, and she gives him food I dont approve of. Point is, i hate her and Idc if she gets pregnant months later or sooner. I dont want to be pregnant with her! So now I'm mad and I vent to friends and they all tell me I should wait til next year to have my second one. Now I'm mad at the fact that people think they can tell me when I can plan my family.(They are persistent on this) I dont listen but I had to vent. Idk what to do. I want a second child but idk if i should wait or start trying after July (I have a trip in July and if I get pregnant now I wont be cleared to fly). And if I sound like a b, I'm sorry but that's how I feel.