Good post Shags, that's one of the benefits of this forum - the ability to ask for help/advice etc.
Couple of points to consider / think about (with the usual - my opinion only disclaimer):
1. from reading your post it appears you might have made your decision to go round too late if you were "almost on top of her". From what you've posted, I'd suggest you should've been going around mid-final (250-300 ft) when it would have been clear the Cessna wasn't going to roll and be clear before you touched down, this would have allowed you to climb and be at 500ft before reaching the runway and then allowing an early crosswind to ensure there was no conflict with the Cessna - it should have been able to roll the Cessna with you going round and still have adequate separation.
2. When going round (aerodrome procedures permitting i.e. dual runways etc.) always keep the runway in sight - fly the dead side or in a position to keep the runway and any traffic visual - the reason you've gone around is generally because of conflicting traffic, keep them in sight.
3. Aviate - Navigate - Communicate, the old favourite - fly the aeroplane. If the radio is too busy to communicate you're intentions (initial or revised), fly to your intentions (revised in this instance) and when you get an opportunity to transmit, update your call with current details.
4. Your reflection that you "let her line up when you were on finals" is an interesting one. While you legally had right of way, you can't "direct traffic", you can only advise your position and intentions and rely on the other pilot to obey the rules. If they don't, you need to alter your plans.