hi tal, welcome to the forum. sorry to hear you're feeling bad
i deal with nutritional approaches to health and the first thing i'll tell you is that building humans takes a large nutritional toll on your body. if you don't make a concerted effort to rebuild nutritional stores after delivery, you can end up depleted. stress just makes things worse as you burn through nutrients even faster as part of the stress response. it can all combine to make you feel pretty low, and correcting nutrients status could go a long way to improve how you feel emotionally.
would you be okay to post a little bit of detail about your day to day diet? if you give me an idea of sample breakfasts, lunches, dinners, snacks and beverages i might be able to spot some imbalances just with that.
can you specify what blood test or tests were done, and will they tell you the actual result with units if you ask? it's important to know - i've found that doctors don't necessarily know what the term 'normal' implies. in some cases, research is showing that being anywhere lower than the very top end of the range can mean you're at greater risk for illness.
pregnancy is a massive nutrient drain but the number one i've run across to date is zinc. i'd be looking for a serum zinc test, and based on the other symptoms you describe i'd be curious about serum copper, serum magnesium, serum b12, serum folate, serum ferritin, and serum 25hydroxyvitamind3. magnesium is particularly relevant for dealing with stress and depression.
anyway hope you found some useful tidbits here, and i hope you can post some more detailed info too. if you do, i can help you interpret findings. hope you feel better soon