When is my bunny fully grown?

So I rescued Penelope from a rescue centre and they couldn’t really give me much information about her or her breed, other than that she thought she was a runt of the litter. From my research and what others have said I believe she is a Lionhead/Mini Rex mix (please correct me if I’m wrong). She is currently 6 months old and is getting quite big, does anyone know when she’ll be classed as fully grown? She started off so tiny so I assumed she would always be a small rabbit.

AAww! She's adorable! Do you know how much she weighs?

Lionheads are typically just under 4 lbs and mini-rexes can be up to 4.5 lbs.

An "average" size rabbit (considering all breeds) is considered to be 5-7 lbs. She 'looks' little to me but photos can be deceiving.

Rabbits are considered adults at 6-7 months.

Omg! My female looks almost identical to your Penelope! Marshmallow is a bright white with black around her eyes. She’s also a Lionhead. Marshmellow is about a year old, and she’s HUGE! Partially because I found out I was feeding her WAY too many fresh veggies. We had to cut back almost 90%. Do you feed veggies to your girl?

Blue eyes said:

AAww! She's adorable! Do you know how much she weighs?

Lionheads are typically just under 4 lbs and mini-rexes can be up to 4.5 lbs.

An "average" size rabbit (considering all breeds) is considered to be 5-7 lbs. She 'looks' little to me but photos can be deceiving.

Rabbits are considered adults at 6-7 months.

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I have just weighed her this morning and she’s around 4.3lbs, is she overweight? She’s active enough and free roam across the house all the time so it’s not like she doesn’t get exercise, she is constantly binkying and running about!

Tara Parker said:

Omg! My female looks almost identical to your Penelope! Marshmallow is a bright white with black around her eyes. She’s also a Lionhead. Marshmellow is about a year old, and she’s HUGE! Partially because I found out I was feeding her WAY too many fresh veggies. We had to cut back almost 90%. Do you feed veggies to your girl?

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I don’t think I’m over feeding her on veggies, she’s free roam across the house so she gets enough exercise! I typically feed her a range of veggies in the morning but nothing I would say that was too excessive? This morning she’s had a few cucumber sticks and a handful of coriander, as well as her morning pellets! I’ll probably give her some other form of veggies this evening as well! I didn’t realise veggies could make them overweight!

Our Vet says they can live on veggies and unlimited hay--he doesn't like pellets in their diet.

Pellets are typically the culprit when it comes to overfeeding.

As for your bunny's weight, with mixed breeds it is better to go by a visual (and feeling them) to determine if they are at the "right" weight. This link should help:
http://www.therabbithouse.com/diet/rabbit-weight.asp

And this is a general guide for what a proper bunny diet looks like (your rabbit is close enough in size to go by this as well):

Could be a twin for our boy, Mr Hoppes.