Hi, have you written out your chord charts? And are you familiar with the circle of 5ths? - a technique used to find the accidentals and key signature of each key. In order to modulate to the tonic minor (which would be F# minor), the easiest way to get there is the pivot on chord 5.
You could finish with a cadence and start the new phrase in D#minor.
You've picked a weird key, and in order to be in the key of D# minor you need to remember the raise the 5th, therefore the c# is raised to a cx (double sharp).
The easiest way to pivot to D# minor would be use chord vi which is the D#m chord (it is chord vi of F# major and is chord i of D# minor).
This particular chord, since it's chord vi of the original key, should not be inverted.
Remember that you must include the accidentals - in minor keys you must raise the 7th as I said therefore you must remember to include a double sharp on the C. Please double check with your teacher if you can! This should be the easiest pivot, and it's how I would choose to modulate to this key.
Edit: Hey, sorry have just seen on a separate thread that someone has already given the same answer as me. (I also have just finished my A level music). If you have any questions feel free to ask.