Citalopram

I have been on Citalopram for approx 20 years, recently had my first blip in over 20 years. Increased from 20mg to 30mg initially, which gave some benefits but not all, so after 10 weeks increased to 40mg. I am feeling so much better after 4 weeks however still have the anxiety and unhelpful scary thoughts. I’m concerned that due to being on the tablet fo so long, that I will never achieve the full benefits. Does anyone have experience of this? I appreciate it’s only 4 weeks, and I need to wait another 2-4 weeks, I just don’t want to have to change tablets.