I'm a Breastfeeding peer supporter, and experience lots of mum's feeling the way you do.
Many babies at this stage enjoy long periods at the breast, your both still learning so as time passes you'll both become more efficient with the feeds. Make sure you get your latch and positioning checked, as this will eliminate insufficient feeding, where your baby has to work unnecessarily harder at the breast.
Other reasons for constant feeding is the heat, growth spurts and cluster feeding. Also babies get comfort from sucking, so since your baby is 10 days old stress from the delivery can still be present.
Regarding your low mood and anxiety, do you feel that this is related to Breastfeeding or being a new mum? It's such early days that you need to be kind to yourself. Let these emotions come and go naturally, don't hold onto these feelings but don't resist them either. I would advise to have a chat with your gp/midwife/health visitor should they not improve. Just to be on the safe side.
I feel sick with nerves when I get anxious, do not pressure yourself to eat 3 meals a day. Try and eat little and often, and sip lots of water, juices etc. Treat yourself each day with your favourite food, bath or book etc. During pregnancy your body lays down extra fat stores for Breastfeeding so drinking fluids and eating little and often won't effect your milk supply.
The pro-lactin and oxytocin hormones released during the feeds should help relax you, but at this stressful early stage it will be hard to notice them.
Also remember sleep deprivation is a huge culprit in affecting your moods and well being. So try and rest as much as possible.
Lastly, by 6 weeks your milk becomes "full milk", it's changing constantly at this transition so don't think this is how you'll baby feed forever.
Good luck and try and get along to a Breastfeeding group or see a bf peer supporter, as they will help you with this difficult stage.