Question on step up basis- property held Joint tenants vs Trust

[Justin Summers]

My mother has a revokable living trust that holds most of her real estate property for the benefit of her 3 children after her death.  (Under 3 million in value) 

There is one property that she was going to leave just to me (her son) to pay me back for money I loaned her years ago..  When she bought the property a few years ago she put it in her personal name and my name as joint tenants with right of survivorship ..  So, that upon her death the property would transfer to me.. She is currently receiving all the rent on the property and takes all the taxes deductions.  I have never claimed it on my taxes. 

My question is this..  If she passes all the properties in the trust will receive a stepped up basis to the current market value at the time of her passing,  But i think the property that we hold title in both our names as JTWRS , I would only receive 50% of the stepped up value, is that correct.?

If we put the property in the name of the trust now and put wording in the trust that the property will transfer to me from the trust after her death I assume I would get the full stepped up basis? 

Bought in 2015 for $150k  .. value at Death $250k   

I'm assuming if we leave the property in both names I would only get a stepped up value to $200k and if we transfer it to the trust I would get $250k basis basically saving $50k worth of capital gains when I sell it..

Any input or feedback would be appreciated.

Just