Because there are guidelines on how long breast milk can be stored, you need to make sure you date all of your pumped milk, according to Women's Health. Most breast milk storage bags come with a space, and you can use masking tape for the outside of bottles. If your baby goes to daycare, make sure to label all of your pumped milk with your child's name, too.

According to the Mayo Clinic, you should store your breast milk in glass or hard plastic, BPA-free containers with caps and lids. If you are storing in bags, make sure to use actual breast milk storage bags and not disposable bottle liners or household plastic bags. To better protect your bagged milk, you can put the bags in a Tupperware container or some other hard container to minimize risk of tearing on fridge and freezer shelves.

If you're having an awesome pumping sesh, it's understandable that you'd want to fill each storage container straight to the top, but be sure to leave a little space in each bottle or bag. Medela, a company for breastfeeding supplies, notes on their website that liquids like breast milk can expand when frozen, and without the space at the top of the container, the bottle or bag could burst.

Pumped milk should go in to a fridge or cooler with an ice pack as soon as possible, but that's not always feasible for pumping moms. If you have stored milk that's sitting out at room temperature, it's good for three to four hours according to the Office on Women's Health website, as long as it's been covered. For very clean milk, the office suggests that the milk could be good for six to eight hours.

For moms who are placing their milk straight in the fridge, the Office on Women's Health suggests your breast milk is good for three to five days, as long as it's very clean. The optimal time to use it is within three days though.

You're in luck if you're trying to build up a stash (or have milk in your fridge that won't be used within three to five days). The Office on Women's Health notes that milk stored in the freezer is best between three to six months, but can be stored for as long as nine months. If you happen to have a deep freezer, your milk could be stored for up to 12 months.

Don't worry if you notice that your breast milk has separated while it's being stored. According to KellyMom, the cream in the milk will rise to the top during storage and only requires you to swirl the milk when you're warming it to mix it all back together. (Don't shake it!)

Not only is milk more likely to fall out and spill in the door of a fridge or freezer, but it also doesn't stay as cold as it should. Lansinoh, a breastfeeding supply company, suggests storing milk in the center of your refrigerator or freezer so it has a consistent temperature and has less of a risk of thawing.

You can combine milk from separate sessions in the same container, but make sure that the milk you're adding to a previously stored amount has been cooled. Adding warm milk to a cool or frozen stash could thaw the breast milk according to Mayo Clinic.

Medela suggests that when you're pumping, try to store between two to five ounces in each container. Depending on how much your baby eats, you can adjust the amount, but it's easier to thaw a small amount of milk and you can minimize your chances of wasting unused milk.

According to the Mayo Clinic, the longer breast milk has been stored, the more it loses vitamin C. Be sure to use the oldest milk in your stash first so that you don't have any breast milk being stored longer than necessary.

Another reason to keep portions in your storage containers small? You have to throw out any milk leftover from a feeding within one to two hours. You can refrigerate it for a little while, but once that two hour mark hits, the leftover milk has to go.

As tempting as it is, you can not refreeze any previously thawed milk. In fact, the Office on Women's Health suggests using thawed milk within 24 hours before tossing it.