Bagnolet to lyon TGV station

I believe you are talking about the Euroline terminus located in Gallieni (The terminus of metro line 3).
From Gallieni to Gare de Lyon, the easiest method (excluding taxi) should be riding on metro. It's not a difficult task.

At Gallieni, take the metro line 3, and get off at Pere Lachaise (3 stops)
At Pere Lachaise, change metro line 2, and get off at Nation (4 stops)
At Nation, change metro line 1, and get off at Gare de Lyon (2 stops)
Normally, it takes around 30 mins on metro from Gallieni to Gare de Lyon, but I am not sure if your walking speed will be affected by bulky luggage... Also, the Euroline bus might be delayed... If you ideal train departed Gare de Lyon at 07:43, your bus must arrive before 06:45, because you have to arrive the train station at least 15 minutes before departure, otherwise you may not be able to catch the train.
I would recommend you to select the next train if possible, or you can take this risk, but you have to pray that bus cannot be late !! and also you have to walk or even run faster !!

GOOD

very useful, thanks ^^