If it has been over one year since your pregnancy then it is very unlikely that you would get any change in its size or shape. Some changes will improve over time but from your description I would suspect that only a tip rhinoplasty could correct the problem.
Widening of the nose with pregnancy is not typically permanent.
If your nose doesn't look the same 1 1/2 years after pregnancy, it probably won't change. I have seen women's noses widen during pregnancy (especially with female fetuses), but this typically subsides as your weight goes back to the pre-pregnancy state.
I'm not sure why you nose is persistently wide. Your OB may be a good source of information.
I hope this is helpful for you.
Post partum nasal widening
There is more fat in the nose, especially around the tip than most people realize
Weight gain can exentuate the width of the nasal tip.
If you feel your weight is a problem post partum, you may benefit as much from dieting as from spending money on a rhinoplasty. If your wieght is where you want it to be, a rhinoplast that targets only the tip fat may be right for you.
Pregnancy can enhance bulbous nose appearance
This is a complication that can occur but infrequently, the enlarging of a nose post pregnancy.
I first would like to see any photos of your face pre-pregnancy, then compare more recent photos. I bet you always had some widening and bulbousness initially. The pregnancies just enhanced the appearance.
Your ONLY option is rhinoplasty. So go see 3 boarded Plastic surgeons.
Wide bulbous nose from pregnancy
Since it has been a year-and-a-half after your last pregnancy, your nose is probably in a permanent state at this point. The bulbousness and bifidity is unlikely to go away at this point and your nose will not return to its pre-pregnancy shape. A rhinoplasty would be your only solution to improve the aesthetics of your nose.
Post- Partum Tip Swelling
Your bulbous tip, present 1 1/2 years after your last pregnancy will probably not improve in the future. I suggest you have a consultation with an experienced rhinoplasty surgeon.
Bulbous overprojected tip
Your bulbous tip may decrease in size slightly over time. However you will probably need a rhinoplasty to reduce the bulbosity to your liking.
A wide nose that has not shrunken down after a year and a half probably will not get any smaller now. If it really bothers you, you may want a tip rhinoplasty.
After this amount of time it should be back to normal.
Since it is not, the best option for you is to see an experienced rhinoplasty surgeon to evaluate your nose and to discuss the options you have to correct this.