Hi,
Congratulations on your pregnancy. I am also 5 motnhs pregnant.. so far rthis time no swelling.
Elevate your feet as much as possible when you are not at work. If you are able to try find somewhere where you can lay down at lunchtime to elevate your feet. Last pg I used to go to my car turn it on and lie down on the back seat so the blood could move back up. TRy to always sleep on your left hand side.
Make sure your doctor cheks your blood pressure every visit. If one of your legs swellsmore than the other, it may be a sign of edema which is the precurser to high blood pressure and can lead to pre-eclampsia. I had all of this with my first baby.He is almost 3 and is doing great even though he was born early at 4lbs 5 oz at 35.5 weeks.
Make sur eyou get some salt with iodine, your body needs it. Adding a little table salt to your meals is good. But stay away from preprepared foods and canned/frozen meals they have super high quantities of salt.
Keep drinking lots of water that is the best thing you can do... the more you drink the better your body copes with eliminating excess water.
Wishing you all the best for the rest of your pregnancy and a happy healthy baby.