If your breasts are sore and lumpy, you're on your way to clogged ducts and possibly a breast infection, so I suggest you take action right away to keep the milk moving out. Weaning is a process, and it takes your body 24 to 48 hours to make any adustment in supply (either to produe more or less milk). If you are at all uncomfortable or engorged, that tells you you're moving too fast.
I suggest warm showers/baths with some gentle massaging (always towards your nipples to help things move out) and regular pumping to comfort. Some moms like to lean into a pan of warm water. Many moms find chilled cabbage leaves soothing and they can reduce swelling. Ibuprofen (up to 800 mg a day) is compatible with breastfeeding and is an antiinflammatory to reduce swelling. If your baby will still nurse and you're not opposed to it, he might be able to help you get comfortable by nursing--the best pump in the world has nothing on a well-latched baby!
I highly, highly recommend you contact your local La Leche League Leader. She can answer all these questions and discuss your personal experience in greater detail over the phone--all LLL services are totally free. Your local LLL groups will also have two excellent books to borrow, "How Weaning Happens" and "Mothering Your Nursing Toddler," which can help you strategize this weaning process so everyone is comfortable and happy. You can find your local LLL Leader's number at www.llli.org.
BTW, there's no rule that says you *have* to stop breastfeeding once your child turns one. The American Academy of Peditrics recommends babies continue to nurse until they are at least one, and thereafter as long as is mutually desired by mom and baby. UNICEF, the World Health Organization and the last U.S. Surgeon General all recommended at least two years of nursing, (which sounds like forever to most American moms because breastfeeding rates are so low here, but is really the norm in other countries). Plus, we're getting into winter and there are germs everywhere, so a little extra immunity boost from some mama's milk can help your little man stay healthy--it's OK to wean down to just a couple of little nursings and hang onto those for health and snuggles for awhile.
Good for you for taking such good care of yourself and your baby!