I think its quite normal unfortunatley! I've been in flip flops for weeks and was reduced to interviewing in converse the other week at work as just could not get my feet into my shoes! BP totally normal, low if anything, and I think you're right that hands and face are more warning signs of pre-eclampsia.
Have had fat feet for weeks now, bp is all good just get your feet right up whenever you can (above your heart if possible-lying on sofa with feet up on the arm of whatever). It's uncomfortable but one of the joys of being pregnant! The weather certainly doesn't help either! Even my flip flops and slippers have been tight for the last few weeks. Thankfully the end is in sight (due tomorrow) and they will go!
It's no good just being 'off your feet' as it at a desk. I was doing some work at my desk at home yesterday and mine were dreadful. You have to sit with you feet up on a chair/sofa, on a pile of cushions so they are raised. Not so easy if you are at work. I would mention it to MW & see what she says but as other posters say, just one of the joys I think
Ive had it for what seems like months. Midwife has kept an eye on it but I don't think they are bothered unless it is in your hands and face as well. It is worse for me when I sit down and my legs are down (like at a desk or driving), if I can sit with my feet up I do! Also, it helps to do those exercises that you are meant to do on long haul flights -circling ankles and moving them up and down. Even better if you can do them with your legs above the level of your heart. I miss my ankles. I never knew how much I should have appreciated them when they were here. Never again will I be so complacent about them!!