Is it normal 5 week after breast aug to feel like there is fluid in breasts?

Sometimes, a little air or fluid can be noticed after an augmentation.  I would wait several months before pursuing any intervention.

Many women feel and hear sloshing and blubbering around implants for a few weeks after breast augmentation. This is especially the case with smooth implants when breast implant displacement (massage) is done after the procedure. Over time, the body should absorb air and fluid so these sounds and sensations disappear. For textured surface implants, fluid around an implant would be somewhat concerning as these implants are supposed to gently stick to your tissues, and a large amount of fluid around them can lead to problems down the road, especially if they are anatomically shaped implants. You should contact your plastics surgeon for an evaluation.

Thank you for your question.  Although it is not unusual to hear or feel a fluid sensation in the early weeks after breast augmentation, this is unusual at 5 weeks.  I suggest you visit your plastic surgeon for an examination and diagnosis.