I don't see your connection in TXL. However, 2:05 in LHR *should* be plenty, even assuming that you have to go from T5->T3. If you're delayed coming into LHR,. I'd say you have about 20 minutes of leeway. Any more than that and you'll be hustling. The best I've ever been able to do from T5 to T3 is 1:10, but the worst was 2:15 (spent mostly in the onward ticketing section at T3 on a Saturday morning because my upgrade was apparently causing some problems.) Things may have changed since I last flew. If you can get your LHR-JFK boarding pass before you hit LHR, by all means do so.