The half life is not 14 days. By day 14 it will be cleared out of your system and your T levels are then probably lower than before starting TRT. The high spikes of T from the injections will increase SHBG and estradiol (E2) and many here would expect that you will feel worse, not better.
100mg/wk is a typical starting dose. Weekly injections feel good at first when they kick in in a couple of weeks or so. The T docks at T receptors, the receptor complex gets pulled into the cell and changes occur to the gene expression in the nucleus of the cell, changes occur in the cell and the bulk changes occur to tissues. This all takes time. It is not like shooting dope.
Many need to inject more than once a week to feel better. I inject every other day, (EOD/E2D). Some inject twice a week or E3D.
If you feel like crap, it could be from E2. What is your serum E2 blood work level and the lab range from the lab report.
For me, lowering my E2 was the key to feeling well. I felt supercharged after 4 weeks on T, by 3 months I felt like crap. E2 is the problem. I felt down the days before my next weekly injection, after a while the down days were 7 days a week and I did not feel any lift from the injection.
98 mg/wk of test cyp took me to 886, adding 250iu HCG took me to 1025.
Are you using T from a pharmacy or gear… possibly fake. Sounds like your T is perhaps fake. If not fake, the T was completely gone at day 14 as expected.
I recommend that you start injecting twice a week or E3D at least.
You need HCG to keep your testes healthy… not shrinking.
Do blood testing 1/2 way through your injection cycle.
If you have thin skin/fat on your quads, you can inject with a #27,28,29 .5" .5ml insulin syringe. Some will use a #25 1" needle. The .5" needle is fine for that location with thin skin and small injection volumes.
The half life of T cyp or eth is more like 5-6 days. How you feel is more important than such numbers… you feel like crap now I guess.
Infrequent injections with large doses create spikes of T that are very high. That drives up E2 production and increases SHBG. SHBG reduces free FT. Creating E2 from FT also reduces the amount of FT. Frequent small doses reduce the spikes and the issues from that. You then have overlapping injections with overlapping release profiles. Ideal TRT would replace T level patterns. Injecting twice a week is simply wrong.
I did not see at first that you have been on HRT for years… some of the above reads for a beginner… sorry.