You have enough points.....finding availability at saver fare rates will be the challenge. (UA has IAD-SIN r/t saver business fares starting at 180K miles.)

If you can't find business saver award availability to SIN directly from IAD, you might consider checking for availability to nearby Asian capitals like BKK, SGN, or HKG. It's relatively inexpensive to fly intra-Asia on some pretty decent low cost carriers like AirAsia or Bangkok Airways. Just get yourself nearby and then hop on a cheap two or three hour flight to SIN.

Another way to approach it would be to check for business saver award availability from LAX or SFO; if you find it, you book that and then just work out the transportation from DC to the West Coast separately. (You could check ORD also but I wouldn't want to use that option in February.)

Feb/Mar is considered high season in SE Asia so finding the exact match may be a challenge. Good luck.