OP , it sounds like you have been through a horrible upsetting experience and are completely filled with guilt. (Catholic guilt at that !) and have tried to grab on to faith to help you through. Which is completely understandable. However you have really got your understanding of 'the rules' a bit topsy-turvy.
The Catholic Church does not have rules 'open to interpretation ' when it comes to matters of sexuality/marriage /family life etc. There are hard and fast teachings on what is and isn't 'a sin'. The withdrawal method is a sin according to the Catholic Church. The only method of family planning (not contraception) that is sanctioned by the Catholic Church was set out in (I think 1968) by the then Pope. In his prophetic encyclical [i]Humanae Vitae[/i] (Of human life), Pope Paul VI taught that “there may be serious reasons for spacing offspring… The Church teaches that in such cases it is morally permissible for spouses to… reserve marital intercourse for infertile times. The spouses are able to plan their families without violating the moral teachings set forth above.’ In this carefully qualified sense, the Church actually supports “birth control” and “family planning”---and the method left open to us is NFP.
So in simple terms the Catholic Church agrees that you can space your children by abstinence during fertile times but that is as far as it goes and you are meant to have a very good reason to do this. The rest of the time it's just 'Gods will'.
Just because I know a lot about it, doesn't mean that I adhere to it. It's bollocks and a way to subjugate women, keeping them pregnant almost their entire child rearing years. Causes poverty and non stop stress.
Your simplest solution is to just forget about contraception and crack on with number 2 and however more you want, then just get your DH to have a Vasectomy. Job done.
Your local priest does not have the authority to change the 'rules'.