One of the perks of breastfeeding is that the milk is free! So, when you're expecting to be able to feed your baby from your own body, the $25-$30 price tag on a tub of formula is total sticker shock. Never been a coupon-clipper? Well hello, Cartwheel.

My husband and I were initially buying the 2 oz packs of liquid formula for convenience, but quickly realized that wasn't financially sustainable.

There are protocols for storing milk for babies. If you're handling breast milk and formula, you have two sets of rules to remember.

Breast milk: Freshly expressed milk needs to get in the fridge ASAP, and then ideally used within 72 hours. Thawed milk should be used the same day. Depending on the type of freezer, you can store milk anywhere from two weeks to a year.

Formula: Formula is good for about an hour once it's been mixed or opened (if it's the ready-to-feed variety). For me, this meant that anywhere I went, I carried powdered formula and water in bottles separately. After your hour window, formula should be refrigerated. If you mixed if yourself, use it within 24 hours (48 hours for pre-made or concentrates.)

Try keeping that straight in your mom brain.

When you breastfeed your baby, you know they're getting a specialized milk with exactly what they need in terms of nutrients, as well as with an immunity booster. With formula, however, there are seemingly endless options to consider. Is it iron-fortified? Hydrolyzed? Organic? Probiotic? What do any of those things mean anyway?

Most babies will be fine with a modified cow's milk or soy milk formula (mine was), but other babies have allergies that require a special (read: expensive) formula. My friend, a mom of triplets, ended up needing to supplement with a lactose-free formula. That sh*t isn't cheap, especially when multiplied by three.

Generally, when you breastfeed on demand, your magical boobies produce the exact amount your baby needs, with each session stimulating more breast milk production. Formula-feeding mamas know how much their baby takes because they are carefully measuring.

When you're doing a combination, it can be hard to know how much your baby needs. You can't always count on "the ladies" to provide enough, so do you follow-up with a bottle of formula or start with formula and top off baby with the breast? It's hard to know.

My personal sanitizing list:

1) Nipple shield

2) Vials of formula powder for diaper bag

3) Bottles for storing formula in the refrigerator

4) Bottles baby actually drinks out of

5) Pumping parts

6) Pacifiers

When you're balancing breast and bottle, you get the best of both worlds, sure. However, you also get the worst. Sanitizing can be a logistical nightmare, so do yourself a favor and develop a system. Those steam clean bags saved this exhausted mom's life.

Breastfeeding is a supply and demand system, so even offering one bottle of formula can diminish your supply. That sucks, but it's an especially rotten deal if your reason for supplementing is low supply. You know that every time you give your baby a bottle, you're missing an opportunity to stimulate milk production. And there's no pump as effective as a hungry newborn.

One way to combat damage to your milk supply is to pump. Yay. I don't know about you, but for me there's nothing more infuriating than pumping for half and hour and getting a paltry half an ounce. Pumping is the worst anyway, but doing it without a big payout takes the cake in degrees of suckage.

When you get such a little amount, you have to decide whether to mix it with formula or not. If you combine them, baby might not take the entire bottle and end up wasting your hard-won liquid gold. On the other hand, if you keep them separate, you have to prepare two separate bottles. More bottles = more work for you.

Perhaps you've heard of nipple confusion. This is a phenomenon in which baby has gone between breast and bottle and gets frustrated because their technique isn't interchangeable. Bottle nipples are generally easier to manage than real ones, which can make some babies "lazy." They may also prefer the taste of formula, causing them to reject the breast entirely. (The reverse is also true, when baby refuses the bottle because, hey, mom's boob is just so much nicer.)

I was able avoid a lot of problems by making bottle-feeding as much like breastfeeding as possible: on my lap with lots of cuddling and only after nursing first.

When you are unable to breastfeed exclusively like you planned, it can really shatter the vision you had for yourself as a mother. I felt like I wasn't enough for my baby, and it was soul-crushing. However, adding formula relieved a lot of my stress, and I knew my mental health was the most important factor in being able to care for my baby well.

If you supplement, you need to brace yourself for the wrath of the sanctimommies. They'll tell you that you're not trying hard enough. You just need to pump through the night (sleeping be damned). You have to relax.

Seriously, can we just not anymore with the breastfeeding vs. formula debate? I'm so tired of moms judging each other's decisions. The way I feed my baby doesn't affect anyone but me and my child.

I supplemented with formula, and I have a perfectly happy, healthy toddler. Yeah, I'll try exclusively breastfeed next time (I expect it will be easier now that I know what the hell I'm doing), but if it's not working, I'd absolutely consider supplementing again.