Medication after surgery does reduce the likelihood of relapse and the need for further surgery.
Are you currently in remission? Did the surgeon remove all active disease?
If not you would want a treatment that works quickly (steroids, EEN or infliximab), and if you are in remission then you will still be thinking of maintenance meds. Your main options for maintenance meds are immunosuppressants (6mp, azathioprine or methotrexate) and biologics (usually starting with Remicade/infliximab or Humira/adalimumab).
As to the significance of the length of your small bowel, do you know how much you had removed? In my opinion the proportion of small bowel that you have left has some bearing on your ability to absorb adequate nutrition but it's not all that easy to predict whether people will have issues with this after resection or not.
Your bowel does take time to adapt after surgery and can adapt very successfully to absorb adequate nutrition.
However it is very important to maintain as much small bowel as possible as your small bowel is essential for nutrition. If you lose too much small bowel, then you may need TPN which has associated risks, and this can ultimately necessitate the need for a small bowel transplant.
I would certainly recommend taking medication in your situation and if your doctor doesn't agree I'd seek a second opinion.
New ulcers can develop within 6 weeks of surgery so it's important to (re)start treatment quickly. There are a couple of reviews of post-operative treatment of Crohn's which may be useful to you
here and
here.
There is a study (abstract
here) that shows that taking metronidazole for 90 days post-op reduces the chance of active disease recurring at the site of anastamosis and increase the chance of being in remission 1 year post-op. I think this would need to be started asap if you wanted to do that. In the study they started 1 week after surgery but after my surgery last summer my GI had me start 2 weeks post-op.