E.,
See if your doc will prescribe a anti-emitic such as Compazine and while you are there have your blood-sugar double checked. High blood sugar caused by gestational diabetes is common and can make you feel alot more exhausted than you should feel, it is also easy to treat so it won't hurt to ask.
Mostly, for now, I urge you to call in the troops. Mother-in-laws, mother, sister , cousin, brother, neices, nephews, and dear sweet hubby...whatever family is available to you to watch the 19 month old, help get major chores done inside and outside to cut it all down to light duty for you.
Get out of the house with the 19 month old. I know the weather has been wierd here in Texas but bundle up the kiddo and get a walk in. It's amazing how fresh air and sunshine can change your point of view up.
Get up before the baby in the morning and do the things that wake you up, coffee, shower, etc., take time to jot down the things you need to do that day (be realistic and kind to yourself). Try to fit those chores in while the baby is occupied in the bouncer or swing. Take naps when the baby is napping..if you have to perform a ritual to trick her into a nap (if you can) like wear her down with some outside play, bring her in, give her a meal, give her a bath and lay her down.
Ideally, it would be great if you could start with a Dr. visit to help with all the physical issues. Followed by a few days of respite, sending the baby to Grandma's for the weekend, while hubby and others take care of the big chores..then implement the other changes when the baby returns when you have a clean emotional, physical clean slate and your surroundings have been refreshed.
Now I know this all may not be feasible to you, not everybody has family available to them. If not, maybe you could check on hiring a neighbor or a local daycare for some ala carte or once a week care.
But, do see your doc soon. If your pancreas is having troublle bearing the load of pregnancy it can make life really hard for you (did you know that during pregnancy we actually make a hormone that fights our pancreas' ability to break down sugars), believe me I understand.
I hope you will give yourself the gift of rest, sometimes it can be hard to ask but if you really feel like the baby is suffering from your lack of energy it's time to swallow your pride and accept the help until you get back on track. AND YOU WILL, I know it.
You are not alone, sister and asking for help is a smart, brave thing to do.
WIshing you the very best,
T.