K.M.
Are you sure YOU want to wean? You only mentioned your husband pressuring you and not knowing anyone else who does extended nursing. If you still want to nurse, it's not unusual for an 18 month old to still be breastfeeding. Sure they don't need to nurse for nutrition, but they nurse for other reasons like comfort during teething or because there is developmental stuff going on at 18 months and they need the comfort and reassurance of mom. So if you like nursing, don't feel like there's anything wrong with continuing. I wouldn't wean for other people, but if you are personally done, there is nothing wrong with stopping either. For me, around 2 years old was when I was personally done. I nursed my kids 25 months and 23 months respectively. Here are some tips that may help:
1. Eliminate nursing one session at a time starting with the one he's least attached to. Leave nursing to sleep as the last one(s) to go.
2. Nurse in one spot, probably his room if that's where he nurses to sleep to help lessen his nursing triggers from other spots. This will be inconvenient, but worth it!
3. Distract and don't offer. But, if he's really persistent you can tell him when you'll nurse again- at naptime, after snacktime, etc. Make it concrete so he understands you'll nurse again.
4. Don't sit down! This was a big trigger with my daughter. Maybe spend a lot of time outdoors/out of the house at the usual nursing times.
5. I'd eliminate one nursing session a week to start, but go quicker or slower depending on how he's doing.
6. Start a routine for going to sleep that involves nursing at the end. Do this while you're working on cutting out the daytime sessions. Then when that's set, move nursing to the next to last thing in the routine. Finally, start decreasing the length of nursing until you eliminate it altogether. I'd work on cutting out the nursing at naptime and leave the bedtime session for last and nurse him to sleep during the night as needed. As he relies less on nursing to sleep during the day, you may find things get easier at night and he'll accept other comfort.
My daughter was not big on self soothing. She was really attached to nursing, but this gradual weaning worked well for her and weaning was mostly drama free and non-traumatic. Good luck!