No.
Transgenders who claim to experience no discrimination still experience significantly higher suicide rate than the general population. Yes, discrimination is associated with an increase, but it cannot explain the significant disparity.
In general, bullying is actually not that significant of a predictor of suicide.
https://www.jahonline.org/article/S1054-139X(20)30687-X/fulltextTwin study that controls for past psychopathy, genes, family environment, etc. finds that a one standard deviation increase in bullying only predicts a 25% increase in the odds of attempting suicide, therefore claiming that discrimination accounts for a significant amount of the disparity is wrong.
A meta analysis of 40 studies finds that the vast majority of LGBT youth who have attempted suicide answer “no” when asked if they’ve personally been the victim of various sorts of anti-LGBT discrimination and bullying
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0245268Similarly, this finds that, the past year suicide attempt rate among trans people reporting having been the victim of zero cases of significant discrimination within the last year was 5.1% or 8.5 times the rate of the general population
https://williamsinstitute.law.ucla.edu/wp-content/uploads/Suicidality-Transgender-Sep-2019.pdf 