You're in trouble.
Here are my recommendations:
- See if you can get a "fast-track" passport renewal. Most countries have the option to get a passport renewed in one or two days by paying an extra fee. Not all can do it outside the country. Call the embassy and see if you can convert your renewal to an urgent fast-track one. If you can then do it. Your problems will be over. This may cost a bit of money, but it's definitely better than not showing up at your own wedding.
- If that is not possible, see if you can get an emergency passport. Embassies will sometimes issue these for lost passports, and you might be able to talk them into doing it in this case. Even if it will only work to get you to Pakistan, that's OK. You can get the renewed passport sent to you when it's done.
- If that doesn't work, see if you can get your old passport back, ideally without stopping the renewal. If you can then bring your flight forward so that you fly out before it expires. If you can also get your passport extended (again preferably without stopping the renewal process) you may be able to use your original flight. However remember your passport has to be valid on the day you land, if that is different from the day you leave. These may be expensive, but remember it's better than missing your own wedding.
- If any of those work then you will actually get to Pakistan for your wedding. Congratulations, all you have to do is get home. If you were able to keep the existing renewal process going, then get it delivered to your home and get someone you know to courier the passport out to you in Pakistan. If you had to stop the renewal to get your passport back then you will need to go and get your passport renewed in Pakistan. Pay whatever you need to get it done as fast as possible.
Many of these options are expensive, but in the long run a few thousand dollars isn't going to compare with the embarrassment of missing your own wedding. And it will be a great story to tell your grandchildren.
Finally, when you are done, please come and write your own answer here about what actually worked for you (or didn't work). This will help future readers.