First - congratulations!
Easy solution - try it for two weeks, and if it doesnt work out, it doesnt work out. Lots of people try and for one of a hundred reasons decide that formula is the best option.
I say two weeks because the first week or so is REALLY hard. Your nipples will probably crack and bleed. Gross, I know, and no one tells you that. It HURT like crazy for a few days any time the baby latches on. On top of that, you are always scared the baby isnt getting enough to eat because you cant really tell. When your milk lets down, you have these weird tingly feelings that take a little while to get used to. Also, when your milk first comes in on day 2 or 3, you get engorged which makes your breasts feel like great big hard bruises. Thats no fun and very alarming, if you were not expecting it. If things get really bad, you get mastitis which makes you feel like you have the worst flu you have ever had in your life. Good news is that you have pain killers from giving birth - take those for breastfeeding. :)
After the first two weeks, things get better. You can pump and let daddy give a night time bottle while you sleep. When you DO get up, you dont have to mess around with fixing a formula bottle - just pop that baby on and doze in the chair. :) Its starts to feel nice to nurse your little baby, and see that sweet little face, mouth latched on, nursing contentedly away. Your husband gets jealous because you and baby are so happy breastfeeding.
When my children got a little older, I could nurse them laying down, which was GREAT! Just laying around on the couch, nursing the baby, watching TV while the husband does the dishes and feeds the other kids. Oh well, babies gotta eat, right?
I work full time and breastfed both of my children until they were at least one. I took a pump to work and pumped in a conference room three times a day. I pumped at home twice a day (my kids were big eaters). It was exhausting, but I was obsessed!
In lots of ways, I think its MORE convenient than formula because you never need to pack a bottle. Taking the big girls to soccer? No problem. Just sit in the car, or in a corner someplace, and discretely nurse. You may be self conscious, but REALLY, no one else cares. I had more people give me positive comments for breastfeeding that I can count, and never had anyone even look at me crosswise, let alone say anything, about the public breastfeeding.
One big motivation for me was the $$. How much does formula cost? @ $40/month? I have no idea because we did not spend one cent on formula. I'm so cheap (and poor) I was ultra committed to breastfeeding to save the money.
Try it - give it a few weeks. If it does not work out for you, your baby, and the rest of your family, switch to formula. If it does work out, great! If not - no problem. Your girls turned out great, right? :)