I need much more information. I ask that you discuss this with your practitioner at your next visit. I know the vascular system makes a big change. If you are someone who exercised a lot prior to being pregnant, please discuss this with your doctor. Your doctor will be able to advise you on how to safely proceed with exercise during pregnancy.
Yeast infections are relatively common.
Please contact your practitioner to make sure there are no other reasons why you are having those symptoms and for treatment as well. My wife is 10 weeks pregnant, but doesn't seem to be gaining weight. Depending on how much your wife can eat and drink and whether or not she is nauseated and has vomiting, it is not uncommon for women to not gain a lot of weight. Her practitioner will follow her closely and make sure she has a steady weight gain during pregnancy. In the presence of a balanced diet, the recommendations are that you supplement your diet with prenatal vitamins.