Is this a failed eyebrow transplant?

What you describe sounds within the realm of normal. The growth will become more regular as time goes on. Over time you will need to trim the transplanted hair to shape your brow aesthetic. 

Typically most of the transplanted eyebrow hairs shed within 2 to 4 weeks post procedure and begin to grow at approximately 12 weeks post procedure. At five months post procedure we typically see about 50% of the result and the full result at nine months post procedure. It is very important to understand prior to undergoing an eyebrow transplant procedure that when the donor hair is taken from the scalp the new eyebrow hair will be the exact color and character of the scalp hair. The scalp hair that is transplanted to the eyebrow does not become more like eyebrow hair it maintains its character even after the transfer to the eyebrow region. In patients with very coarse hair sometimes it is beneficial to perform Follicular Unit Extraction and harvest finer hairs from lower on the neck. Most importantly, it is imperative when choosing a surgeon that you choose someone with extensive experience performing eyebrow transplants. An experienced hair transplant surgeon is not necessarily an experienced eyebrow transplant surgeon. Orthopedic surgeons fix broken bones but you wouldn't have an orthopedic surgeon fix your broken nose, which is a bone. A plastic surgeon would fix your broken nasal bone. The same is true for eyebrow transplants. Choose a surgeon with a multitude of before and after photo results without make up that you think look natural.

The best reassurance will likely be from your doctor who can examine you.  Give your doctor a call. In general, hairs fall out few weeks after surgery.It takes 6 to 12 months to see results.

Unfortunately the eyebrow transplant will assume the character of where the hair was taken ie the donor site.  That means it will grow and will require frequent trimming.  Also expect the hair to be somewhat different  than the surrounding brow hair as once again it will assume the identity of where it was taken from .

Eyebrow transplant involves using head hair to transplant into the eyebrows. Head hair and eyebrow hair grow very differently and have different texture. It is important to understand that when transplanted into the eyebrows the head hair will still grow as it did in the scalp. Often after an eyebrow transplant maintenance is required to trim eyebrow hairs and use some product to keep them under control.

I generally tell my patietns that the waiting time is usually 8 months for any transplant. I would go back and see your surgeon to get answers or get a second opinion