Is it really low supply?

The following points may describe what your baby is doing.

If your baby wants to feed very frequently, this is normal. Most young babies need at least 8 feeds in 24 hours and may continue to feed frequently even as they get older.
If your baby is feeding less frequently and for less time, this may be normal as they become more efficient at emptying the breast. Check your baby’s wet nappies and growth to see that they are still getting enough milk.
If your baby has been putting on weight rapidly but now weight gains have slowed, this can be normal for a breastfed baby. Read more about weight gains.

If your baby is fussy and doesn’t settle after feeds, they may have other needs. They may be uncomfortable, tired, overstimulated or just want to be held. A top-up breastfeed can help.
If your baby wants to feed all the time, it may be because they are in pain. Sucking at the breast comforts babies and this is normal. But if your baby also has a lot of wet and dirty nappies each day and the poos are green, frothy or explosive, you may actually have an oversupply. You may not realise that you make a lot of milk because your upset baby is always feeding for comfort and your breasts are soft. There are ways to manage oversupply.

If you have small breasts, you can still provide your baby with all the breastmilk they need. Your breast size doesn't make any difference to how much milk you can make. Your baby may just need to feed a little more often.
If that early engorgement has gone and your breasts have stopped feeling full, this is normal. Your breasts have settled down to make just the right amount for your baby. Your breasts will still make milk when your baby feeds.
If your breasts feel empty towards the end of the day, that can be normal too. When babies feed frequently and remove milk well from the breasts, they won’t feel big and full. This is a good sign. The more well drained your breasts are, the faster they will make milk. You don’t have to wait for breasts to 'fill up'. Keep feeding your baby.
If you don’t feel your let-down reflex, it’s probably still working fine. Many mums don’t notice any physical sensations. Look for your baby’s sucking patterns. A rhythmical suck-swallow pattern with regular swallowing means your let-down is working and your baby is getting milk.

If you can’t express milk, that’s okay. Expressing is a skill that many mothers take time to learn. The amount you can express isn’t the same as how much milk your breasts make. Your baby is more efficient at removing milk than a breast pump.
If you express straight after a breastfeed you may not get much at all. Your breasts are never empty but your baby will have taken most of what’s there. Wait about half an hour and try again.