Should I be worried if my implant still hasn't completely dropped after 6 months?

It is unlikely that they will drop any further BUT your results are quite acceptable.  You should discuss your concerns with your PS.

Thank you for the photographs.  It is unlikely that the position of your implant will change after 6 months.  It appears that the left breast is fuller.  There may several reasons for this. It is best to revisit with your PS concerning this matter.Dr. ES

If the implant is
high due to inadequate release of muscle or incomplete descent or capsular
contracture, maintaining the submuscular position is reasonable.  Discuss your concerns with your surgeon

At 6 months, the amount of future change expected is minimal for most women. Small, tight breasts do take longer to stretch and accomodate the implant than larger breasts and thus you may see some improvement in the coming months. From the photos, your implants do not look terribly high, but there is a nipple position difference. It is difficult to tell from your photos (especially without a front preop), but it is common for augmentations to reveal asymmetries between the breasts. These often become more noticeable after implants. Even a minor difference in nipple position can look significantly asymmetric after an augmentation. A simple lift on one side can correct this.

I don't think I would expect much change from hereon out. From the before photos it appears that there is some limitation of lower pole of the breast, and with as large as an implant as you have, more than half will be above the nipple line. Many would find this a good result, but if the upper pole fullness disturbs you, you may need to consider smaller implantsAll the best. 

Thank you for your question and pictures.  You can expect to have continued 'dropping' of the implant for up to one year.  After that, gravity and tissue stretch will continue to 'soften up' the appearance of your upper breast and give you a more natural appearance.To clarify, implants don't actually 'drop' (at least they shouldn't) after surgery.  What actually happens is that the chest muscle and breast skin in the upper breast continue to stretch and relax giving the appearance that the upper part of the breast is getting flatter (and thus the implant appears to have 'dropped'). In reality, the implant stays in the same position and the relaxed muscle and skin allows the implant appearance in the upper breast to go from a bulging look to a more natural appearance.