Ok, you seem to have enough blood bags but currently, the game will check just 1 slot. If one slot doesn't have 4 blood bags, the game will assume you don't have enough blood bags. Upcoming update should be able to fix this problem.
For temporary solution, you need to empty one of your soap slot. You can do this by taking a bath at your home & then wait 15 minutes. Keep doing this to deplete the soap. Each bath consumes 10g soap so this might take awhile. Once you have an empty slot, go to the clinic to buy again 4 blood bags in a single go.