Unless your first baby was not wetting enough diapers and not gaining weight, you were producing enough. You most likely were given poor advice and supplemented without true medical reason. It's fairly common, and unfortunately, most doctors, nurses, and midwives don't really know much about breastfeeding. ALWAYS check with an international board certified lactation consultant (IBCLC) before supplementing with formula. Most of the time, it's not actually medically necessary.
Just because your baby wants to nurse often does NOT mean that you're not making enough. Babies are supposed to be hungry a lot - especially if they're breastfed. A newborn's stomach is only about as big as a marble. Of course they're going to need to eat often.
The only reliable way to know if you're making enough milk is to keep track of wet diapers (baby should be wetting 5-6 a day after the first week) and weight gain (baby should be back up to his birth weight around 2 weeks old and gaining normally after that). Most women who think their supply is low are mistaken, unfortunately, and it doesn't help that so many medical professionals can give really poor advice and recommend formula so quickly. If your baby is wetting enough diapers and gaining weight, they're getting enough and your supply is fine.
See here:
Cluster Feeding: http://www.kellymom.com/babyconcerns/fussy-evening.html
Is Baby Getting Enough Milk? http://www.kellymom.com/bf/supply/enough-milk.html
Is Your Milk Supply Really Low? http://www.kellymom.com/bf/supply/low-supply.html#supply
Growth Spurts: http://www.kellymom.com/bf/normal/growth-spurt.html
Frequent Nursing: http://www.kellymom.com/bf/normal/frequent-nursing.html
My Baby Is Fussy! Is Something Wrong? http://www.kellymom.com/babyconcerns/fussybaby.html
Even if baby is not gaining weight very quickly, formula supplements are not necessarily needed. See here: "How might I increase baby's weight gain?" http://www.kellymom.com/babyconcerns/growth/weight-gain_increase.html
Your boobs don't have to get large or full feeling at all, really. Not every woman experiences engorgement. That doesn't mean you can't produce enough milk. See here: http://www.kellymom.com/bf/supply/breast-fullness.html Breast fullness and softness are NOT an indicator of supply.
The best thing you can do to prepare for breastfeeding during pregnancy is educate yourself. Knowledge is power.
I highly recommend this book - "So That's What They're For!" http://www.amazon.com/gp/product/159337285X/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=1580620418&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1F7RKWZVK7AHGG9KA3SY
I also highly recommend visiting La Leche League group meetings while you're still pregnant. They're completely free, and the leaders will even come help you for free after your baby is born. Check here to find a group near you: http://www.llli.org/WebUS.html
Bottom line:
~ put your baby to the breast as soon as possible after birth (within 30 minutes to an hour after birth, preferably)
~ let them nurse as often as they need to for as long as they need to (milk is produced on a supply/demand basis - your body knows how much to make based on how often your baby nurses)
~ avoid supplementing unless it's absolutely medically indicated (as that reduces time spent at the breast, fills up the baby so they won't want to nurse as much, and can contribute to nipple confusion/bottle preference)
~ avoid artificial nipples for the first 4-6 weeks, since pacifiers and bottles can interfere with breastfeeding when introduced before it is well established
~ avoid pumping and bottlefeeding milk unless baby absolutely cannot latch onto the breast (pumps cannot stimulate the breast like a nursing baby, so pumping should not replace nursing unless you must be separated from your baby or they can't latch on)