Iud and pregnancy

I have been on Mirena for a year and 8months and my husband and I decided not to use condoms anymore because I am on birth control and would be more protected from getting pregnant again because we already have a 1year old..well to make a long story short I have been having the same symptoms as my first pregnancy for a while and decided to take a pregnancy test it came back positive but faint(Friday) so I decided to wait a couple of days to take another which was today and that test also came back positive but a little darker..what are the pros and cons of me being able to keep the baby or miscarriage please help?

I have scheduled a appointment for Wednesday and will keep you updated on what happened.