autoimmune thyroiditis

Hi all, I got full-blown hyperthyroidism for 2-3mths duration. Also hypertension due to hyperthyroidism.

Initial presentation: (Date:29/4/15)
FT4 45.5pmol/L (12.0-22.0)
TSH <0.005 mIU/L (0.270-4.20)

Thyroid Antibodies:
Thyroid Receptor Antibody (TRabs) <0.3 IU/L NEGATIVE <1.8
Thyroid Stiumlating Immunoglobulin (TSI) <1 % NEGATIVE
Thyroid Peroxidase Ab L <5 IU/mL (5-34) NEGATIVE
Thyroglobulin Ab H 217 IU/mL (10-115) POSITIVE*

Other tests:
Erythrocyte Sedimentation Rate: 4 mm/hr (1-10)

Most Recent Thyroid Function Test: (27/5/15)
FT4 HH 29.8 pmol/L (12.0-22.0)
TSH LL 0.006 mIU/L (0.270-4.20)

Other tests:
Slightly lipaemic

Ultrasound of Thyroid:
Indication- Primary hyperthyroidism

Right lobe of thyroid measures: 6 x 2 x 1.8 cm
Left lobe of thyroid measures: 5.9 x 1.8 x 1.6cm
Isthmus measures 0.5 cm

Normal echotexture without nodules or calcification.
Diffuse, mildly increased vascularity of thyroid gland noted.
Cervical lymph nodes appear normal.

IMPRESSION:
Diffuse thyroiditis without focal mass.
ABNORMAL

working diagnosis: autoimmune thyroiditis
current medication:
15mg carbimazole (changing to 10m carbimazole in 2 wks times)
2.5mg amlodipine
10m propanalol (2 times daily)

So does anyone think they know what it could be?
My doctor can't really say whether it's Hashimoto or something else.
It definitely isnt graves.
She said it could be Hashi- toxicosis (initial hyper state, then hypo)
I'm really afraid that one day I would suddenly be hypo .
Oh, and is the size of my thyroid normal, what is the normal size for human?
Im going to USA soon, the only difference is the change from carbimazole to methimazole right.

Thanks and much appreciated!