Please mention your travel date and the departure times of your trains.

one for 7th of may and one for someone else for 20th of june and the train from brussels from 8.17 and from nimes at 15.59

The 8:17 TGV from Brussels doesn't have pass holder seats anymore on both dates. The TGVs from Brussels have a limited quota for pass holders unfortunately.

Workarounds:

1. Use a regular train to Lille-Flandres and book the TGV from there.
2. Book a regular ticket Brussels-Lille and a pass reservation from Lille.

You can book TGV pass reservations on www.raileurope.com (desktop website only), which is cheaper than via Interrail.

The 15:59 AVE can't be booked online. Reservations are only available at a ticket office in Spain. In France, you can speak with the staff before boarding the train and then pay them after boarding. They're used to it and well aware of the situation.

would it work if i took the 8.17 (and then chill at paris airport for two hours) or 10.17 (might be cutting it close because it arrives at 11.53) to paris airport train station and then take the 12.01 from there to lyon part dieu? 

The train goes directly from Brussels or Lille to Lyon, no need to switch trains in Paris CDG Airport. Just stay on the train.

For Brussels to TGV Charles de Gaulle, there aren't any pass holder reservations available either, on both dates. You can see that for yourself on raileurope.com, where they propose the regular fare instead.

Where exactly do you start? Maybe we can come up with a workable alternative for both those dates.

on the intterail site i can make a reservation for it though

I also see it on Rail Europe now. Maybe someone cancelled a reservation…

Then book another reservation in the same train to Nîmes.

i cant go to lyon? i need to end up in barcelona so thats the same train from lyon and nimes right? also, do you think the 10.17 if it should arrive at 11.53 that i can make the 12.01 to lyon? i dont know if trains to paris often have a delay or not

The 10:17 from Brussels continues to Lyon (and Nîmes, Montpellier) at 11:59. It's the same train.

@BrendanDB for some reason i cant make reservations for the train to go to lyon directly, only until paris airport.

Yes, because SNCF have implemented a quota for pass holders and for Brussels to Lyon, that quota has already been reached.

As @rvdborgt already said, if you provide us insight in your travel plans, so knowing where you start, there’s a good alternative by making a reservation from Lille to Lyon, combining it with an ordinary (non-interrail Brussels-Lille) ticket or a reservation free itinerary via Kortrijk or Tournai. This way you circumvent the quota as well.

ohh sorry i read your comment wrong, i can make reservations on the same train thats genius sorry thank you so much!!!!!

i think im good now, just two reservations on one train, maybe more expensive but it fine haha thank you

i come from rotterdam, so i dont think i have another option than to go though brussels

would this be the best option then?

10.17 bruxelles midi to paris airport cdg - 11.53

11.59 - 14.00 same train different seat to lyon 

14.32 train to barcelona 

or is 32 minutes transfer time too short then? 

Depends on what you regards as "best”. Cheapest? Fastest? Best views?

The less it costs the better, I am a student I do not have that much money haha, but in this case i guess the fastest without too much risk of missing a transfer so i can get to barcelona that day.