Almost everything OTC is ok for pregnancy after the first trimester. Don't take aspirin ever. Robitussin for use as a decongestant (PE or Guifenesin syrup) will help on the bad days. Dymatapp has the tendency to make you drowsy. I believe Mucinex is also just Guifenesin, so you can use that too....I've just never tried that.
The problem with stuffy noses and sneezing during pregnancy is that it's probably not because of an actual cold, but a result of your pregnancy hormones. You could take something to decongest yourself if you are too stuffed up, but it's not really going to help much if you don't have a cold. You can try hot tea and cayenne pepper also helps to make your nose run
Vapor rubs can be soothing. You can also use a humidifier or a vaporizer and there is nothing harmful about their long term use and will keep your stretching skin hydrated as well. Drink lots of water.