Always it is best to place lingual fixed retainer rather than removable. Because even though am not an orthodontist am telling this with my own experience as i have undergone orthodontic treatment. I kept removable retainer in upper arch and fixed in lower. I removed my braces 3 years back after 8 months my upper retainer broke upper arch got relapsed and lower arch still am having lingual fixed retainer. It has not relapsed at all.
So always best to go for permanent retainers
Next Steps
Go and visit a nearby orthodontist
Health Tips
Since u told u r not much affordable it is better to take ur old retainer to orthodontist so that if any adjustments can be done he will be doing