I am worried I am bottoming out. When I lift my arms up my nipples are all the way on the top of the implant.

I am sorry to hear about/see the problem you are having after breast augmentation surgery. You may wish to post photographs with your next question, preferably with your arms by your side, for specific  assessment and advice.
 Generally speaking, signs of breast implant bottoming out include: 
1. Breast implant "sits" too low on the chest wall.
2.  Excessive palpability or visibility of the breast implant along the lower breast pole.
3.  Nipple/areola complex seems to be sitting relatively high, because the breast implants have settled too low. 
4. Discomfort along the lower breast pole (secondary to pressure from the underlying implant).
5. Relative paucity of upper pole breast implant volume compared to lower pole volume.
6. Increased visibility of a infra mammary fold scar (higher on the breast mound).
  Patients with breast implant bottoming out usually benefit from revisionary breast surgery which typically involves capsulorraphy (internal suture repair). Sometimes, depending mainly on the patient's history and physical examination, I will also use additional supportive materials such as acellular dermal matrix or biosynthetic mesh. This procedure serves to reconstruct the lower poles of the breasts and prevent migration of the breast implants too far inferiorly. Associated issues with positioning of nipple/areola complexes should improve with this operation.  In my opinion, careful attention to postoperative activity restrictions is one of the keys to success. In my practice, I ask patients to keep their elbows by their sides for at least first two weeks after the procedure is performed. Longer-term, certain activity (depending on exactly what procedure is performed) may also be restricted in an effort to avoid  the potential for implant malposition recurrence.
Best wishes.

Thank you for your questions. Sorry to hear you are having concerns. Without an in-person examination or at least pictures to reference, I cannot offer specific advice. Without knowing the details of the problem, it is impossible to offer potential solutions. Your best bet would be a consultation with a local plastic surgeon who is board certified by the American Board of Plastic Surgery.Best of luck!