Preseed with pull out method

using preseed can you still get pregnant if the guy pulls out while using this product ? I found out back in Dec 2 I was pregnant and it ended in a miscarriage. I want a baby and he wants to wait until his best friends wife ends up pregnant first so we can have kids growing up together since my boyfriend and his friend grew up together. Or in all honesty do you all think I should not use preseed and give up having a baby... it took me 6 years just to have my 2nd who just ended in a miscarriage... I feel greedy wanting a baby.... I just want one because I miss having a baby.. my son will be 7 this year and I don't like such a huge age gap...HE ALSO KNOWS I AM.USING PRESEED AND IS IT OKAY WITH IT BTW LADIES WHO JUDGE !